Invasive Micropapillary Carcinoma of the Breast: An Update

Preoperative lymph node metastasis risk assessment in invasive micropapillary carcinoma of the breast: development of a machine learning-based predictive model with a web-based calculator

BACKGROUND

Invasive micropapillary carcinoma (IMPC) is a rare subtype of breast cancer characterized by a high risk of lymph node metastasis (LNM). The study aimed to identify predictors of LNM and to develop a machine learning (ML)-based risk prediction model for patients with breast IMPC.

METHODS

We retrospectively analyzed a cohort of 229 patients diagnosed with breast IMPC between 2019 and 2021. Patients were randomly assigned to training and test sets in a 7:3 ratio. Independent risk factors for LNM were identified using univariable and multivariable logistic regression analyses. Thirteen ML algorithms were trained and compared to determine the optimal model. Model performance was evaluated using the area under the curve (AUC), calibration plots, and decision curve analysis. Internal validation was performed using 100 iterations of tenfold cross-validation.

RESULTS

LNM was present in 158 patients (69%). Tumor size, histological grade, progesterone receptor staining intensity, and lymphovascular invasion were identified as independent predictors of LNM (all p < 0.05). Among the 13 ML models, logistic regression (LR) demonstrated the best performance, achieving an AUC of 0.88 in the test set. A nomogram based on the LR model was constructed to facilitate clinical application, showing excellent calibration, clinical utility, and a classification accuracy of 76% (95% confidence interval: 70%-82%). The median AUC across cross-validation iterations was 0.83 (interquartile range: 0.76-0.91).

CONCLUSIONS

This study identified key predictors of LNM in breast IMPC and developed a well-calibrated nomogram to support individualized treatment decision-making.

Adipokines in Breast Cancer: Decoding Genetic and Proteomic Mechanisms Underlying Migration, Invasion, and Proliferation

Background

Adipokines, bioactive peptides secreted by adipose tissue, appear to contribute to breast cancer development and progression. While numerous studies suggest their role in promoting tumor growth, the exact mechanisms of their involvement are not yet completely understood.

Methods

In this project, varying concentrations of recombinant human adipokines (Leptin, Lipocalin-2, PAI-1, and Resistin) were used to study their effects on four selected breast cancer cell lines (EVSA-T, MCF-7, MDA-MB-231, and SK-Br-3). Over a five-day proliferation phase, linear growth was assessed by calculating doubling times and malignancy-associated changes in gene and protein expression were identified using quantitative TaqMan real-time PCR and multiplex protein analysis. Migration and invasion behaviors were quantified using specialized Boyden chamber assays.

Results

We found significant, adipokine-mediated genetic and proteomic alterations, with PCR showing an up to 6-fold increase of numerous malignancy-associated genes after adipokine-supplementation. Adipokines further altered protein secretion, such as raising the concentrations of different tumor-associated proteins up to 13-fold. Effects on proliferation varied, however, with most approaches showing significant enhancement in growth kinetics. A concentration-dependent increase in migration and invasion was generally observed, with no significant reductions in any approaches.

Conclusion

We could show a robust promoting effect of several adipokines on different breast cancer cells in vitro. Understanding the interaction between adipose tissue and breast cancer cells opens potential avenues for innovative breast cancer prevention and therapy strategies. Our findings indicate that antibodies against specific adipokines could become a beneficial component of clinical breast cancer treatment in the future.

Failure to progress: breast and prostate cancer cell lines in developing targeted therapies

Developing anticancer drugs from preclinical to clinical takes approximately a decade in a cutting-edge biomedical lab and still 97% of most fail at clinical trials. Cell line usage is critical in expediting the advancement of anticancer therapies. Yet developing appropriate cell lines has been challenging and overcoming these obstacles whilst implementing a systematic approach of utilizing 3D models that recapitulate the tumour microenvironment is prudent. Using a robust and continuous supply of cell lines representing all ethnic groups from all locales is necessary to capture the evolving tumour landscape in culture. Next, the conversion of these models to systems on a chip that can by way of high throughput cytotoxic assays identify drug leads for clinical trials should fast-track drug development while markedly improving success rates. In this review, we describe the challenges that have hindered the progression of cell line models over seven decades and methods to overcome this. We outline the gaps in breast and prostate cancer cell line pathology and racial representation alongside their involvement in relevant drug development.

Deciphering the composition and key driver genes of breast invasive micropapillary carcinoma by multi-omics analysis

In this study, we delved into the intrinsic cellular components and transcriptomic signatures characterizing breast-invasive micropapillary carcinoma (IMPC). Employing bulk RNA sequencing, we conducted differential gene expression and functional profiles across breast cancer tissues. Single-cell transcriptome sequencing was performed on mixed IMPC samples. Moreover, a multicenter retrospective cohort of IMPC patients validated the critical role of KRT80. Our findings illuminated heightened activity in redox reactions and metabolism-related functions within IMPC compared to other tissue types. The single-cell atlas of IMPC demonstrated substantial heterogeneity predominantly driven by two distinct cell subsets: epithelioid and interstitial cells. Pseudotime analysis unveiled unique cell trajectories, and we found positive correlation between KRT80 expression and clinicopathological characteristics in IMPC. High KRT80 expression was associated with shorter overall survival for IMPC patients. This investigation unmasked extensive heterogeneity within breast IMPC tumors, delineating lineage distinctions across diverse cell clusters. It unveils potential prospective therapeutic targets with clinical relevance.

An overview of invasive micropapillary carcinoma of the breast: past, present, and future

Invasive micropapillary carcinoma of the breast (IMPC) exhibits a unique micropapillary structure and "inside-out" growth pattern. Despite its extremely low incidence, IMPC has attracted considerable attention owing to its poor prognosis. Since Siriaunkgul and Tavassoli first proposed the term IMPC in 1993 to describe its morphological characteristics, with tumor cell clusters arranged in a pseudopapillary structure within the glandular cavity, its diagnostic rate has substantially increased. Based on the in-depth study of IMPC, a more comprehensive understanding of its epidemiology, clinicopathological features, and diagnostic criteria has been achieved in recent years. The pathogenesis and specific therapeutic targets of IMPC remain unclear. However, numerous studies have delved into its high-risk biological behavior. This review discusses the opportunities and challenges associated with IMPC.

The differences between pure and mixed invasive micropapillary breast cancer: the epithelial-mesenchymal transition molecules and prognosis

PURPOSE

Invasive micropapillary carcinoma (IMPC) of the breast is known for its high metastatic potential, but the definition of pure and mixed IMPC remains unclear. This retrospective cohort study aims to investigate the prognostic significance of the micropapillary component ratio and the expression of critical molecules of epithelial-mesenchymal transition (EMT), including E-cadherin (E-cad), N-cadherin (N-cad), CD44s, and β-catenin (β-cat), in distinguishing between pure and mixed IMPCs.

METHODS

We analyzed 100 cases of locally advanced IMPC between 2000 and 2018 and excluded patients who received neoadjuvant chemotherapy. Pure IMPC was defined as having a micropapillary component of over 90%. A comprehensive recording of prognostic parameters was conducted. The IMPC areas were analyzed using the immunohistochemical (IHC) staining method on the microarray set for pure and mixed IMPC patients. Pearson's chi-square, Fisher's exact tests, Kaplan-Meier analysis, and Cox proportional hazards analysis were employed.

RESULTS

The comparative survival analysis of the entire group, based on overall survival (OS) and disease-free survival (DFS), revealed no significant difference between the pure and mixed groups (P = 0.480, HR = 1.474 [0.502-4.325] and P = 0.390, HR = 1.587 [0.550-4.640], respectively). However, in the pure IMPC group, certain factors were found to be associated with a higher risk of short survival. These factors included skin involvement (P = 0.050), pT3&4 category (P = 0.006), a ratio of intraductal component (> 5%) (P = 0.032), and high-level expression of N-cad (P = 0.020). Notably, none of the risk factors identified for short OS in pure IMPC cases were observed as significant risks in mixed cases and vice versa. Furthermore, N-cad was identified as a poor prognostic marker for OS in pure IMPCs (P = 0.002).

CONCLUSION

The selection of a 90% ratio for classifying pure IMPCs revealed significant differences in certain molecular and prognostic parameters between pure and mixed groups. Notably, the involvement of N-cadherin in the epithelial-mesenchymal transition (EMT) process provided crucial insights for predicting OS and DFS while also distinguishing between the two groups. These findings strongly support the notion that the pure IMPC subgroup represents a distinct entity characterized by unique molecular characteristics and behavioral patterns.

Micropapillary breast carcinoma in comparison with invasive duct carcinoma. Does it have an aggressive clinical presentation and an unfavorable prognosis?

BACKGROUND

Invasive micropapillary carcinoma (IMPC) was first proposed as an entity by Fisher et al. In the 2003 World Health Organization (WHO) guidelines for histologic classification of the breast tumors. IMPC was recognized as a distinct, rare histological subtype of breast cancer. IMPC is emerging as a surgical and oncological challenge due to its tendency to manifest as a palpable mass, larger in size and higher in grade than IDC with more rate of lymphovascular invasion (LVI) and lymph node (LN) involvement, which changes the surgical and adjuvant management plans to more aggressive, with comparative prognosis still being a point of ongoing debate.

AIM OF THE STUDY

In this study, we compared the clinicopathological characteristics, survival and surgical management of breast cancer patients having invasive micropapillary carcinoma pathological subtype in comparison to those having invasive duct carcinoma.

METHOD

This is a comparative study on female patients presented to Baheya center for early detection and treatment of breast cancer, in the period from 2015 to 2022 diagnosed with breast cancer of IMPC subtype in one group compared with another group of invasive duct carcinoma. we analyzed 138 cases of IMPC and 500 cases of IDC.

RESULTS

The incidence of LVI in the IMPC group was 88.3% in comparison to 47.0% in the IDC group (p < 0.001). IMPC had a higher incidence of lymph node involvement than the IDC group (68.8% and 56% respectively). IMPC had a lower rate of breast conserving surgery (26% vs.37.8%) compared with IDC. The survival analysis indicated that IMPC patients had no significant difference in overall survival compared with IDC patients and no differences were noted in locoregional recurrence rate and distant metastasis rate comparing IMPCs with IDCs.

CONCLUSION

The results from our PSM analysis suggested that there was no statistically significant difference in prognosis between IMPC and IDC patients after matching them with similar clinical characteristics. However, IMPC was found to be more aggressive, had larger tumor size, greater lymph node metastasis rate and an advanced tumor stage.

MiR-30c suppresses the proliferation, metastasis and polarity reversal of tumor cell clusters by targeting MTDH in invasive micropapillary carcinoma of the breast

Purpose

Invasive micropapillary carcinoma (IMPC) of the breast has a high propensity for lymphovascular invasion and axillary lymph node metastasis and displays an 'inside-out' growth pattern, but the molecular mechanism of invasion, metastasis and cell polarity reversal in IMPC is unclear.

Methods

and Patients: Cell growth curves, tumor sphere formation assays, transwell assays, mouse xenograft model and immunofluorescence were evaluated to investigate the effects of miR-30c and MTDH. Dual luciferase reporter assays was performed to confirm that the MTDH (metadherin) 3'UTR bound to miR-30c. MiRNA in situ hybridization (ISH) and immunohistochemistry (IHC) were carried out on IMPC patient tissues for miR-30c and MTDH expression, respectively.

Results

We found miR-30c as a tumor suppressor gene in cell proliferation, metastasis and polarity reversal of IMPC. Overexpression of miR-30c inhibited cell growth and metastasis in vitro and in vivo. MiR-30c could directly target the MTDH 3'UTR. MiR-30c overexpression inhibited breast cancer cell proliferation, invasion and metastasis by targeting MTDH. Moreover, miR-30c/MTDH axis could also regulate cell polarity reversal of IMPC. By ISH and IHC analyses, miR-30c and MTDH were significantly correlated with tumor size, lymph nodule status and tumor grade, the 'inside-out' growth pattern, overall survival (OS) and disease-free survival (DFS) in IMPC patients.

Conclusions

Overall, miR-30c/MTDH axis was responsible for tumor proliferation, metastasis and polarity reversal. It may provide promising therapeutic targets and prognostic biomarkers for patients with IMPC.

Invasive papillary carcinoma of the breast: A case report

Invasive papillary carcinoma (IPC) of the breast is a rare form of cancer. The current report documents a case of IPC characterized by a large tumor size and skin involvement. Surgical exploration revealed no evidence of axillary lymph node metastasis in breast cancer. Due to financial constraints, the patient opted solely for anastrozole endocrine therapy at a dosage of 1 mg/day for a period of 5 years post-surgery, foregoing other treatments such as radiotherapy and chemotherapy. Since discharge, 2.5 years have passed, during which the patient has been followed up via phone every 3 months, showing a good prognosis. A literature review indicated that IPC is prevalent amongst the elderly population and can be misdiagnosed due to its morphological, cytomorphological and immunophenotypic overlap with other types of papillary neoplasms. This tumor exhibits a more favorable prognosis compared with IDC, primarily attributed to its advantageous gene and molecular expression patterns, coupled with its decreased invasiveness. Despite limited evidence-based research on the treatment of IPC, the present case report, albeit with limitations, underscores the importance of avoiding over-treatment and suggests the feasibility of combining surgery with endocrine therapy for IPC.

Comprehensive Immunohistochemical Analysis of Epithelial-Mesenchymal Transition Biomarkers in the Invasive Micropapillary Cancer of the Breast

Background: Invasive micropapillary carcinoma (IMPC) of the breast is commonly associated with a poor prognosis due to its high incidence of lymphovascular invasion and lymph node metastasis (LNM). Our study is aimed at investigating the prognostic significance of the expressions of E-cadherin (E-cad), N-cadherin (N-cad), CD44s, and β-catenin (β-cat). In addition, it is aimed at deciphering the consistency of these markers between the IMPC, the invasive breast carcinoma, no-special type (IBC-NST), and LNM components in the same IMPC cases. Methods: Sixty-two IMPC cases with LNM from 1996 to 2018 were analyzed. Immunohistochemical staining was performed separately on the three regions for each patient. Statistical analyses included Kaplan-Meier, Cox regression, and McNemar's statistical tests. Results: Loss of CD44 expression in IMPC, IBC-NST, and LNM areas was associated with poor prognosis in overall survival (OS) (p = 0.010, p < 0.0005, p = 0.025). Loss of CD44 expression in the IBC-NST, gain of N-cad expression in the IMPC, and loss of β-cat expression in the LNM areas were indicators of poor prognosis in disease-free survival (DFS) (p = 0.005, p = 0.041, p = 0.009). Conclusion: Our evaluation of this rare subtype, focusing on the expression of key epithelial-mesenchymal transition (EMT) molecules, revealed that it shares characteristics with the IBC-NST component within mixed tumors. Notably, contrary to expectations, a reduction in CD44 expression was found to adversely affect both OS and DFS. By conducting staining procedures simultaneously across three regions within the same patient, a novel approach has provided valuable insights into the mechanisms of EMT.

Correlation Analysis of Digital Mammography, Ultrasonography, and Pathologic Features in Pure Invasive Micropapillary Carcinoma of the Breast (PIMPC)

Purpose

This study determined the digital mammography and ultrasonography imaging features of pure invasive micropapillary carcinoma of the breast (PIMPC) and the correlation with pathologic features.

Patients Methods

Nineteen patients diagnosed with PIMPC at Yantaishan Hospital from October 2015 to February 2022 were included in the study group. Forty patients with breast masses diagnosed as nonspecific invasive ductal carcinoma of the breast (NIDC) from July to December 2021 were included in the control group. Digital mammography and ultrasonography features were compared between the two groups.

Results

Patients with PIMPC had a younger age profile compared to patients with NIDC (P=0.017). Moreover, PIMPC masses were smaller than NIDC masses (P=0.040). Imaging features analysis revealed significant differences in age groups (<45 years: χ²=5.971, P=0.044) and the presence of spiculations or the crab claw sign (χ²=8.583, P=0.004) between patients with PIMPC and NIDC. However, there were no statistically significant differences in the presence of calcifications, blood flow grading, pathologic molecular subtypes between the study and control groups. The Ki-67 proliferative index (χ²=1.052, P=0.389), vascular invasion (χ²=2.263, P=0.197), and lymph node metastasis (χ²=1.968, P=0.386) showed no significant differences between PIMPC and NIDC patients.

Conclusion

PIMPC imaging features show specificity, such as tiny breast masses, spiculated edges, or crab claw-like patterns, and malignant signs appeared when the lesion was <2 cm in diameter. PIMPC mainly occurs in middle-aged women 45-59 y of age. Patients with PIMPC and NIDC of the breast are frequently associated with lymph node metastases and greater than one-half of the cases (74%) were shown to have a Ki-67 index >30%, suggesting a significant risk of recurrence and metastasis. Early therapeutic care for these patients is crucial. These results warrant further validation with additional samples from several centers due to the limited single-center sample size in the current study.

Log odds of positive lymph nodes (LODDS)-based novel nomogram for survival estimation in patients with invasive micropapillary carcinoma of the breast

BACKGROUND

Invasive micropapillary carcinoma (IMPC) of the breast is known for its high propensity for lymph node (LN) invasion. Inadequate LN dissection may compromise the precision of prognostic assessments. This study introduces a log odds of positive lymph nodes (LODDS) method to address this issue and develops a novel LODDS-based nomogram to provide accurate prognostic information.

METHODS

The study analyzed data from 1,901 patients with breast IMPC from the Surveillance, Epidemiology, and End Results database. It assessed the relationships between LODDS and the number of excised LN (eLN), positive LN (pLN), and the pLN ratio (pLNR), identifying an optimal threshold value using a restricted cubic spline method. Predictive factors were identified by the Cox least absolute shrinkage and selection operator (Cox-LASSO) regression and validated through multivariate Cox regression to construct a nomogram. The model's accuracy, discrimination, and utility were assessed. The study also explored the consequences of excluding LODDS from the nomogram and compared its effectiveness with the tumor-node-metastasis (TNM) staging system.

RESULTS

LODDS improved N status classification by identifying heterogeneity in patients with pLN ratios of 0% (pLN =0) or 100% (pLN =eLN) and setting -1.08 as the ideal cutoff. Five independent prognostic factors for breast cancer-specific survival (BCSS) were identified: tumor size, N status, LODDS, progesterone receptor status, and histological grade. The LODDS-based nomogram achieved a strong concordance index of 0.802 (95% CI: 0.741-0.863), surpassing both the version without LODDS and the conventional TNM staging in all tests.

CONCLUSIONS

For breast IMPC, LODDS served as an independent prognostic factor, its effectiveness unaffected by the anatomical LN count, enhancing the accuracy of N staging. The LODDS-based nomogram showed promise in offering more personalized prognostic information.

Integrating X-ray phase-contrast imaging and histology for comparative evaluation of breast tissue malignancies in virtual histology analysis

Detecting breast tissue alterations is essential for cancer diagnosis. However, inherent bidimensionality limits histological procedures' effectiveness in identifying these changes. Our study applies a 3D virtual histology method based on X-ray phase-contrast microtomography (PhC μ CT), performed at a synchrotron facility, to investigate breast tissue samples including different types of lesions, namely intraductal papilloma, micropapillary intracystic carcinoma, and invasive lobular carcinoma. One-to-one comparisons of X-ray and histological images explore the clinical potential of 3D X-ray virtual histology. Results show that PhC μ CT technique provides high spatial resolution and soft tissue sensitivity, while being non-destructive, not requiring a dedicated sample processing and being compatible with conventional histology. PhC μ CT can enhance the visualization of morphological characteristics such as stromal tissue, fibrovascular core, terminal duct lobular unit, stromal/epithelium interface, basement membrane, and adipocytes. Despite not reaching the (sub) cellular level, the three-dimensionality of PhC μ CT images allows to depict in-depth alterations of the breast tissues, potentially revealing pathologically relevant details missed by a single histological section. Compared to serial sectioning, PhC μ CT allows the virtual investigation of the sample volume along any orientation, possibly guiding the pathologist in the choice of the most suitable cutting plane. Overall, PhC μ CT virtual histology holds great promise as a tool adding to conventional histology for improving efficiency, accessibility, and diagnostic accuracy of pathological evaluation.

Invasive micropapillary carcinoma of the breast and bilateral ovarian mature cystic teratoma with benign Brenner tumor in a postmenopausal woman - An uncommon occurrence

The synchronous occurrence of bilateral ovarian tumors and breast malignancy often raise the suspicion of a Krukenberg tumor or a hereditary breast and ovarian cancer syndrome, both of which are uncommon in clinical practice. A 58-years-old postmenopausal woman had a right breast lump and was diagnosed as infiltrating duct carcinoma, no special type, and incidentally detected bilateral adnexal mass with the clinical suspicion of Krukenberg tumor. However, following the radical surgical excision of the right breast and bilateral ovaries, the right breast showed invasive micropapillary carcinoma (IMPC) while the ovaries showed mature cystic teratoma (MCT) with benign Brenner tumor. IMPC of the breast along with bilateral ovarian MCT with benign Brenner tumor is an unusual clinical occurrence in a postmenopausal female and thus worthy of documentation. It should be categorized as a non-hereditary synchronous tumor. The histomorphology augmented by immunohistochemistry and appropriate clinical context is pivotal in rendering a correct diagnosis.

Radiological characteristics of invasive micropapillary carcinoma of the breast

AIM

To analyse the various imaging features of invasive micropapillary carcinoma (IMPC), a distinct variant of breast cancer, by mammography, ultrasound, and contrast-enhanced mammography.

MATERIALS AND METHODS

This study included 68 female patients with histopathologically proven invasive micropapillary carcinoma who underwent mammography, ultrasound, and contrast-enhanced mammography examinations. The findings encountered by each imaging tool were analysed using the Breast Imaging Reporting and Data System (BI-RADS) lexicon.

RESULTS

In this retrospective study, 64.7% of cases were of the pure form of IMPC. Most of the cases showed an aggressive clinical course, with lymphovascular invasion noted in 76.5% of cases, while 60.3% of cases showed associated pathological lymphadenopathy. The N3 stage was reported in 25% of cases. On analysing the mammographic and ultrasound imaging findings, a significant association between irregular shape and a non-circumscribed margin with IMPC was found. Associated calcification was noted in 47% of cases. Pathological enhancement of moderate or marked conspicuity was noted in cases that underwent contrast-enhanced mammography, with the most commonly encountered finding being enhancing irregular and non-circumscribed masses.

CONCLUSION

The mammographic and ultrasound imaging features of IMPC are indistinguishable from other aggressive types of breast cancer. At contrast-enhanced mammography examination, pathological enhancement of moderate to marked conspicuity was shown in all cases. The observed strong association of IMPC with lymphovascular invasion and lymph node metastasis with higher nodal stage in this study mandate meticulous sonographic examination of the axilla, as well as the infra, and supraclavicular regions if pathological axillary lymphadenopathy was noted.

Critical Roles of SRC-3 in the Development and Progression of Breast Cancer, Rendering It a Prospective Clinical Target

Breast cancer (BCa) is the most frequently diagnosed malignant tumor in women and is also one of the leading causes of cancer-related death. Most breast tumors are hormone-dependent and estrogen signaling plays a critical role in promoting the survival and malignant behaviors of these cells. Estrogen signaling involves ligand-activated cytoplasmic estrogen receptors that translocate to the nucleus with various co-regulators, such as steroid receptor co-activator (SRC) family members, and bind to the promoters of target genes and regulate their expression. SRC-3 is a member of this family that interacts with, and enhances, the transcriptional activity of the ligand activated estrogen receptor. Although SRC-3 has important roles in normal homeostasis and developmental processes, it has been shown to be amplified and overexpressed in breast cancer and to promote malignancy. The malignancy-promoting potential of SRC-3 is diverse and involves both promoting malignant behavior of tumor cells and creating a tumor microenvironment that has an immunosuppressive phenotype. SRC-3 also inhibits the recruitment of tumor-infiltrating lymphocytes with effector function and promotes stemness. Furthermore, SRC-3 is also involved in the development of resistance to hormone therapy and immunotherapy during breast cancer treatment. The versatility of SRC-3 in promoting breast cancer malignancy in this way makes it a good target, and methodical targeting of SRC-3 probably will be important for the success of breast cancer treatment.

A web-based novel model for predicting prognostic value in patients with invasive micropapillary carcinoma in breast cancer: a real-world data retrospective cohort study

Invasive micropapillary carcinoma (IMPC) accounts for less than 2% of all invasive breast cancers and usually associates with poor survival, so we investigated the prognostic factors for IMPC using a large population-based database and designed a web-based novel model. Clinicopathological prognostic factors were evaluated using the Surveillance, Epidemiology, and End Results (SEER) database. Multivariate Cox regression analysis was performed to evaluate the prognostic value of variables on the overall survival. A web-based nomogram was finally constructed to predict the survival probability. The model was validated in an external dataset. A web-based model, combined with age, radiation, clinical stage, and hormone receptor (HR) immunochemistry status four prognostic factors, was constructed. The C-index (0.714, 95% CI 0.683-0.741), calibration curves, and decision curves showed that this model was superior in prediction. By determining the cut-off values, high-risk group and low-risk group were divided. The Kaplan-Meier survival curves showed that these two groups had significantly different survival rates (P < 0.0001). The result of C-index, calibration curves, and Kaplan-Meier survival curves were consistent in the validation cohort. The novel nomogram with four risk factors resulted in accurate prognostic prediction for IMPC.

Nomograms for predicting overall survival and cancer-specific survival in patients with invasive micropapillary carcinoma: Based on the SEER database

BACKGROUND

Invasive micropapillary carcinoma (IMPC) is a rare subtype of breast cancer that lacks a prognostic prediction model. Its treatment and prognostic factors remain controversial. Our study aimed to develop nomograms to predict overall survival (OS) and cancer-specific survival (CSS) in IMPC patients.

METHODS

A total of 2149 patients confirmed to have IMPC between 2003 and 2018 were selected from the Surveillance, Epidemiology and End Results (SEER) database. They were divided into training and validation cohorts. Univariate and multivariate Cox regression analyses were used to identify significant independent prognostic factors. The nomograms were used to predict 3- and 5-year OS and CSS. The training and validation cohorts were used to verify the nomograms internally and externally. The predictive capability of the nomograms was evaluated by the consistency index (C-index), calibration curve, receiver operating characteristic (ROC) curve and decision curve analysis (DCA) curve.

RESULTS

In the study, 2149 IMPC patients were randomized to a training group (n = 1611) and a validation group (n = 538). Age, T stage, N stage, ER, radiotherapy, and surgery were identified as independent prognostic factors for OS and CSS. These variables were selected to construct nomograms for IMPC. The C-index (0.768 for OS and 0.811 for CSS) and the time-dependent AUC (>0.7) indicated satisfactory discriminative ability of the nomograms. Additionally, DCA showed that the nomograms had higher clinical value than traditional TNM tumor staging.

CONCLUSIONS

The models can accurately predict the prognosis of IMPC patients and can aid in providing individualized treatment for patients.

Metabolome Sequencing Reveals that Protein Arginine-N-Methyltransferase 1 Promotes the Progression of Invasive Micropapillary Carcinoma of the Breast and Predicts a Poor Prognosis

Invasive micropapillary carcinoma (IMPC) of the breast is a special histopathologic type of cancer with a high recurrence rate and the biological features of invasion and metastasis. Previous spatial transcriptome studies indicated extensive metabolic reprogramming in IMPC, which contributes to tumor cell heterogeneity. However, the impact of metabolome alterations on IMPC biological behavior is unclear. Herein, endogenous metabolite-targeted metabolomic analysis was done on frozen tumor tissue samples from 25 patients with breast IMPC and 34 patients with invasive ductal carcinoma not otherwise specified (IDC-NOS) by liquid chromatography-mass spectrometry. An IMPC-like state, which is an intermediate transitional morphologic phenotype between IMPC and IDC-NOS, was observed. The metabolic type of IMPC and IDC-NOS was related to breast cancer molecular type. Arginine methylation modification and 4-hydroxy-phenylpyruvate metabolic changes play a major role in the metabolic reprogramming of IMPC. High protein arginine-N-methyltransferase (PRMT) 1 expression was an independent factor related to the poor prognosis of patients with IMPC in terms of disease-free survival. PRMT1 promoted H4R3me2a, which induced tumor cell proliferation via cell cycle regulation and facilitated tumor cell metastasis via the tumor necrosis factor signaling pathway. This study identified the metabolic type-related features and intermediate transition morphology of IMPC. The identification of potential targets of PRMT1 has the potential to provide a basis for the precise diagnosis and treatment of breast IMPC.

Invasive Micropapillary Carcinoma of the Breast With Solid Papillary Carcinoma: A Case Report

Invasive micropapillary carcinoma and Solid papillary carcinomas are rare histologic subtypes of breast cancer. Co-existence of tumors of the breast like invasive ductal and lobular carcinomas, or invasive ductal carcinoma and mucinous carcinomas have been reported before. But the existence of invasive micropapillary carcinoma with solid papillary carcinoma is a rare occurrence. Here, we are reporting a rare case of a 60-year-old female with a mass in her left breast. The histopathology report showed a tumor containing these two histologic subtypes. Recognition of all tumor subtypes is necessary, as this can impact the treatment strategy.

Molecular Pathology of Micropapillary Carcinomas: Is Characteristic Morphology Related to Molecular Mechanisms?

Micropapillary carcinoma is an entity defined histologically in many organs. It is associated with lymph node metastasis and poor prognosis. The main mechanism for its histopathologic appearance is reverse polarization. Although the studies on this subject are limited, carcinomas with micropapillary morphology observed in different organs are examined by immunohistochemical and molecular methods. Differences are shown in these tumors compared with conventional carcinomas regarding the rate of somatic mutations, mRNA and miRNA expressions, and protein expression levels. TP53 , PIK3CA , TERT , KRAS , EGFR , MYC , FGFR1 , BRAF , AKT1 , HER2/ERBB2 , CCND1 , and APC mutations, which genes frequently detected in solid tumors, have also been detected in invasive micropapillary carcinoma (IMPC) in various organs. 6q chromosome loss, DNAH9 , FOXO3 , SEC. 63 , and FMN2 gene mutations associated with cell polarity or cell structure and skeleton have also been detected in IMPCs. Among the proteins that affect cell polarity, RAC1, placoglobin, as well as CLDNs, LIN7A, ZEB1, CLDN1, DLG1, CDH1 (E-cadherin), OCLN, AFDN/AF6, ZEB1, SNAI2, ITGA1 (integrin alpha 1), ITGB1 (integrin beta 1), RHOA, Jagged-1 (JAG1) mRNAs differentially express between IMPC and conventional carcinomas. Prediction of prognosis and targeted therapy may benefit from the understanding of molecular mechanisms of micropapillary morphology. This review describes the molecular pathologic mechanisms underlying the micropapillary changes of cancers in various organs in a cell polarity-related dimension.

Label-free detection of invasive micropapillary carcinoma of the breast using multiphoton microscopy

Invasive micropapillary carcinoma of the breast (IMPC) is a rare form of breast cancer with unique histological features, and is associated with high axillary lymph node metastasis and poor clinical prognosis. Thus, IMPC should be diagnosed in time to improve the treatment and management of patients. In this study, multiphoton microscopy (MPM) is used to label-free visualize the morphological features of IMPC. Our results demonstrate that MPM images are well in agreement with hematoxylin and eosin staining and epithelial membrane antigen staining, indicating MPM is comparable to traditional histological analysis in identifying the tissue structure and cell morphology. Statistical analysis shows significant differences in the circumference and area of the glandular lumen and cancer nest between the different IMPC cell clusters with complete glandular lumen morphology, and also shows difference in collagen length, width, and orientation, indicating the invasive ability of different morphologies of IMPC may be different.

Development and validation of nomograms to predict survival in patients with invasive micropapillary carcinoma of the breast

OBJECTIVES

The present study aimed to develop and validate nomograms to predict the survival of patients with breast invasive micropapillary carcinoma (IMPC) to aid objective decision-making.

DESIGN

Prognostic factors were identified using Cox proportional hazards regression analyses and used to construct nomograms to predict overall survival (OS) and breast cancer-specific survival (BCSS) at 3 and 5 years. Kaplan-Meier analysis, calibration curves, the area under the curve (AUC) and the concordance index (C-index) evaluated the nomograms' performance. Decision curve analysis (DCA), integrated discrimination improvement (IDI) and net reclassification improvement (NRI) were used to compare the nomograms with the American Joint Committee on Cancer (AJCC) staging system.

SETTING

Patient data were collected from the Surveillance, Epidemiology, and End Results (SEER) database. This database holds data related to the incidence of cancer acquired from 18 population-based cancer registries in the US.

PARTICIPANTS

We ruled out 1893 patients and allowed the incorporation of 1340 patients into the present study.

RESULTS

The C-index of the AJCC8 stage was lower than that of the OS nomogram (0.670 vs 0.766) and the OS nomograms had higher AUCs than the AJCC8 stage (3 years: 0.839 vs 0.735, 5 years: 0.787 vs 0.658). On calibration plots, the predicted and actual outcomes agreed well, and DCA revealed that the nomograms had better clinical utility compared with the conventional prognosis tool. In the training cohort, the NRI for OS was 0.227, and for BCSS was 0.182, while the IDI for OS was 0.070, and for BCSS was 0.078 (both p<0.001), confirming its accuracy. The Kaplan-Meier curves for nomogram-based risk stratification showed significant differences (p<0.001).

CONCLUSIONS

The nomograms showed excellent discrimination and clinical utility to predict OS and BCSS at 3 and 5 years, and could identify high-risk patients, thus providing IMPC patients with personalised treatment strategies.

PRMT3 regulates the progression of invasive micropapillary carcinoma of the breast

Invasive micropapillary carcinoma (IMPC) is a special histopathological subtype of breast cancer. Clinically, IMPC exhibits a higher incidence of lymphovascular invasion and lymph node metastasis compared with that of invasive ductal carcinoma (IDC), the most common type. However, the metabolic characteristics and related mechanisms underlying malignant IMPC biological behaviors are unknown. We performed large-scale targeted metabolomics analysis on resected tumors obtained from chemotherapy-naïve IMPC (n = 25) and IDC (n = 26) patients to investigate metabolic alterations, and we integrated mass spectrometry analysis, RNA sequencing, and ChIP-sequencing data to elucidate the potential molecular mechanisms. The metabolomics revealed distinct metabolic profiles between IMPC and IDC. For IMPC patients, the metabolomic profile was characterized by significantly high levels of arginine methylation marks, and protein arginine methyltransferase 3 (PRMT3) was identified as a critical regulator that catalyzed the formation of these arginine methylation marks. Notably, overexpression of PRMT3 was an independent risk factor for poor IMPC prognosis. Furthermore, we demonstrated that PRMT3 was a key regulator of breast cancer cell proliferation and metastasis both in vitro and in vivo, and treatment with a preclinical PRMT3 inhibitor decreased the xenograft tumorigenic capacity. Mechanistically, PRMT3 regulated the endoplasmic reticulum (ER) stress signaling pathway by facilitating histone H4 arginine 3 asymmetric dimethylation (H4R3me2a), which may endow breast cancer cells with great proliferative and metastatic capacity. Our findings highlight PRMT3 importance in regulating the malignant biological behavior of IMPC and suggest that small-molecule inhibitors of PRMT3 activity might be promising breast cancer treatments.

The presence of retraction clefts correlates with lymphovascular invasion and lymph node metastasis and predicts poor outcome: Analysis of 2497 breast cancer patients

Some invasive breast carcinomas are surrounded by a clear space that separate the tumor cells from the adjacent stroma, similar to invasive micropapillary carcinoma (IMPC), but lack the thin strands of connective tissue that separate the cells and characteristic "inside-out" growth pattern of IMPC on immunohistochemical stain for EMA. We consider the presence of the retraction clefts a common phenomenon that may present as a precursor stage of IMPC (PSIMPC). In this study, a total of 2497 cases of invasive breast carcinomas were prospectively collected. Among 2497 cases of breast cancer, 949 (38.0 %) cases were PSIMPC, 200 (8.0 %) cases were IMPC and 1348 (54.0 %) cases were IBC-NST. LVI was seen in128 of 200 (64 %) IMPC and 364 of 948 (38.0 %) PSIMPC, in contrast to 246 of 1341 (18 %) IBC-NST (P < 0.001). Lymph node metastasis was seen in 147 of 200 (73.4 %) IMPC and 551 of 949 (58 %) PSIMPC, in contrast to 563 of 1345 (42 %) IBC-NST (P < 0.001). The 5-year disease-free survival (DFS) and overall survival (OS) of PSIMPC were 76.8 % and 87.6 %, compared to 63.2 % and 85.9 % in IMPC, 86.2 % and 93.7 % in IBC-NST. PSIMPC demonstrated a more favorable DFS and OS compared to IMPC, but worse DFS and OS compared to IBC-NST. Cox and logistic regression analysis showed that PSIMPC was an independent predictor of DFS and OS. Our findings suggest that the presence of retraction clefts is a precursor state of IMPC, exhibiting IMPC-like features, such as higher incidence of lymphovascular invasion, lymph node metastasis and more aggressive clinical behavior.

Analysis of Prognostic Factors and Construction of Prognostic Models for Invasive Micropapillary Carcinoma of the Breast

OBJECTIVE

To compare and analyze the clinical characteristics of invasive micropapillary carcinoma (IMPC) of the breast (IMPC-B) and invasive ductal carcinoma (IDC) of the breast (IDC-B) and establish a prognostic model of IMPC-B.

METHODS

We retrospectively analyzed data for patients diagnosed with breast cancer in the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2018 and screened 581 patients with IMPC and 1325 patients with IDC. We compared age, race, laterality, tumor site, histological grade, type of surgery, radiation, chemotherapy, whether the first primary tumor, T stage, N stage, M stage, and molecular type between IMPC-B and IDC-B and draw survival curves of IMPC-B and IDC-B. The relationship between clinical factors and prognosis was investigated by univariate analysis using the Log-rank test and multivariate analysis of the Cox proportional hazards regression model. A risk scoring model was constructed based on independent risk factors to distinguish high-risk and low-risk patients; in addition, a nomogram was created to predict patient survival.

RESULTS

There were differences between the two groups in the age of onset, race, tumor site, histological grade, type of surgery, N stage, and molecular type (p < 0.05). Overall survival was decreased in IMPC-B compared with IDC-B (p < 0.05). The prognosis of IMPC-B was significantly correlated with histological grade, whether the first primary tumor, type of surgery, radiotherapy, chemotherapy, T stage, and N stage. Based on the relationship between the above factors and overall survival prognosis, the risk score model we constructed can effectively distinguish high-risk and low-risk patients (p < 0.05). The established nomogram had better performance in predicting survival in patients with IMPC-B (C - index = 0.78).

CONCLUSION

IMPC-B has a worse prognosis than IDC-B, with earlier age of onset, higher histological grade, and later N stage, and luminal breast cancer is the main type. The nomogram can well predict the prognosis of patients with IMPC-B, which has a high clinical reference value and provides a scientific basis for clinical treatment.

Nomogram for predicting overall survival in patients with invasive micropapillary carcinoma after breast-conserving surgery: A population-based analysis

Background

Due to the loss of prediction of overall survival (OS) for patients with invasive micropapillary carcinoma (IMPC) after breast-conserving surgery (BCS), this study aimed to construct a nomogram for predicting OS in IMPC patients after BCS.

Methods

In total, 481 eligible cases staged 0-III IMPC from 2000 to 2016 were retrieved from the SEER database. A nomogram was built based on the variables selected by LASSO regression to predict the 3-year and 5-year probabilities of OS.

Results

A total of 336 patients were randomly assigned to the training cohort and 145 cases in the validation cohort. The LASSO regression revealed that six variables (age at diagnosis, AJCC stage, marital status, ER status, PR status, and chemotherapy) were predictive variables of OS, and then a nomogram model and an easy-to-use online tool were constructed. The C-indices 0.771 in the training cohort and 0.715 in the validation cohort suggested the robustness of the model. The AUC values for 3-year and 5-year OS in the training cohort were 0.782, 0.790, and 0.674, and 0.682 in the validation cohort, respectively. Based on the cutoff values of 147.23 and 222.44 scores calculated by X-tile analysis, participants in the low-risk group (≤147.23 scores) had a more favorable OS in comparison with those in the medium (>147.23, but <222.44 scores)- and high-risk groups (≥222.44 scores).

Conclusions

By risk stratification, this model is expected to provide a precise and personalized prediction of the cumulative risk and guide treatment decision-making in improving OS strategies for IMPC patients.

Polyploid giant cancer cells and cancer progression

Polyploid giant cancer cells (PGCCs) are an important feature of cellular atypia, the detailed mechanisms of their formation and function remain unclear. PGCCs were previously thought to be derived from repeated mitosis/cytokinesis failure, with no intrinsic ability to proliferate and divide. However, recently, PGCCs have been confirmed to have cancer stem cell (CSC)-like characteristics, and generate progeny cells through asymmetric division, which express epithelial-mesenchymal transition-related markers to promote invasion and migration. The formation of PGCCs can be attributed to multiple stimulating factors, including hypoxia, chemotherapeutic reagents, and radiation, can induce the formation of PGCCs, by regulating the cell cycle and cell fusion-related protein expression. The properties of CSCs suggest that PGCCs can be induced to differentiate into non-tumor cells, and produce erythrocytes composed of embryonic hemoglobin, which have a high affinity for oxygen, and thereby allow PGCCs survival from the severe hypoxia. The number of PGCCs is associated with metastasis, chemoradiotherapy resistance, and recurrence of malignant tumors. Targeting relevant proteins or signaling pathways related with the formation and transdifferentiation of adipose tissue and cartilage in PGCCs may provide new strategies for solid tumor therapy.

Invasive micropapillary breast carcinoma: A retrospective study on the clinical imaging features and pathologic findings

Purpose

To describe the clinical imaging and pathological features of invasive micropapillary breast carcinoma (IMPC), including breast mammography, sonography, magnetic resonance imaging (MRI), and molecular imaging findings.

Patients and methods

We retrospectively reviewed our institution's surgical pathology database and identified 65 patients with pathologically proven IMBC; 63/65 patients had available imaging results. Two radiologists retrospectively reviewed all imaging evaluations according to the Breast Imaging Reporting / Data System (BI-RADS) Lexicon. Clinical and histopathologic features, receptor statuses, and clinical follow-up data were recorded.

Results

Sixty-three patients were admitted with palpable abnormalities; one patient's mammogram revealed no abnormality (3.3%, 1/32), whereas 31 had abnormal mammograms (31/32, 96.8%) demonstrating 37 lesions. Twenty-four had irregular, spiculated masses, 12 had microcalcifications, and 19 had architectural distortion. Sonography detected 69 masses (54 patients), characterized by irregular shapes (61/69, 88.4%), hypoechoic structures (50/69, 72.4%), angular or spiculated margins (38/69, 55.1%; 30/69, 43.4%), echogenic halo (8/69, 11.5%), and abnormal vascularity (52/69, 75.3%). MRI detected 68 lesions (52 patients); 59/68 (86.8%) appeared as masses with angular or spiculated margins (32/68, 47.1%; 35/68, 51.4%), 58 exhibited irregular or lobulated shapes (58/68, 89.7%), 29 displayed heterogeneous internal enhancement (29/68, 42.5%), and 64 demonstrated type II or III washout kinetic curves (37/68, 55%; 27/68, 40%). Breast molecular imaging showed mild-to-moderate radiotracer uptake in 15 focal areas among 13 patients. Thirty-two, 38, and 43 patients had abnormal lymph nodes identified mammographically, by breast sonography, and by MRI, respectively. Immunohistochemistry revealed high estrogen receptor (90.5%), high progesterone receptor (71.6%), and low HER-2 (26.4%) positivity.

Conclusion

IMPC mammography, sonography, and MRI clinical imaging features highly suggest malignancy. Breast molecular imaging also contributed to the diagnosis. IMPC's invasiveness correlated well with regional lymph node metastasis. Radiologists and surgeons should be more attentive to these imaging findings and additional clinical and pathological IMPC features.

COX-2 expression in mammary invasive micropapillary carcinoma is associated with prognostic factors and acts as a potential therapeutic target in comparative oncology

Pure human and canine mammary invasive micropapillary carcinoma is a rare malignant epithelial tumor accounting for 0.9 to 2% of all invasive mammary carcinomas and present a high rate of lymphatic invasion and metastasis, with unfavorable prognosis. Surgery and chemotherapy are standard treatments for almost all mammary cancer in both species, as well as hormonal and target therapies available for human patients. However, depending on the patient's clinical staging, satisfactory therapeutic results for invasive micropapillary carcinoma are a challenge due to its high capacity of invasion and metastasis. Cyclooxygenase-2 (COX-2) isoform is an important enzyme stimulated by cytokines, growth factors and oncogenes activation to synthetizes prostaglandins in inflammatory process. COX-2 overexpression is associated with angiogenesis and invasion and contributes to cancer development, disease progression, tumor recurrence and regional lymph node metastasis in human and canine mammary carcinomas. This enzyme can be targeted by non-steroidal anti-inflammatory drugs and its inhibition can reduce tumor growth and metastasis in several cancer types. Given the similarity between both species, the present study aims to elucidate the involvement of COX-2 mRNA and protein expression in canine (cIMPC) and human (hIMPC) pure invasive mammary micropapillary carcinoma, with clinicopathological and survival data. Twenty-nine cases of cIMPC and 17 cases of hIMPC were analyzed regarding histologic type, grade, age, tumor size, lymph node condition, extracapsular extension, inflammatory infiltrate and immunophenotype. When available, information on adjuvant treatment, recurrence, metastasis and overall survival were collected. The present study demonstrated COX-2 protein expression in 65.5% of cIMPC and 92.3% of hIMPC, and an association with more advanced histological grades in bitches and higher Ki67 in women. COX-2 mRNA expression was significantly higher in cIMPC than in hIMPC, and its expression was not associated with COX-2 protein expression in both species. COX-2 mRNA expression was associated with negative-ER hIMPC as well as higher Ki67. cIMPC demonstrated proportional early development, more regional metastasis, and a prevalence of negative estrogen receptor, than hIMPC. This is the first time COX-2 expression is associated with negative prognostic factors in both cIMPC and hIMPC, besides the overexpression of COX-2 protein in such unfavorable histological type, which suggests that COX-2 can act as a potential target in IMPC.

Abnormality of Apico-Basal Polarity in Adenocarcinoma

Apico–basal polarity is a fundamental property of the epithelium that functions as a barrier, holds cells together, and determines the directions of absorption and secretion. Apico–basal polarity is regulated by extracellular matrix‐integrin binding and downstream signaling pathways, including focal adhesion kinase, rouse‐sarcoma oncogene (SRC), and RHO/RHO‐associated kinase (ROCK). Loss of epithelial cell polarity plays a critical role in the progression of cancer cells. However, in differentiated carcinomas, polarity is not completely lost but dysregulated. Recent progress with a three‐dimensional culture of primary cancer cells allowed for studies of the mechanism underlying the abnormality of polarity in differentiated cancers, including flexible switching of polarity status in response to the microenvironment. Invasive micropapillary carcinoma (MPC) is one of the histopathological phenotypes of adenocarcinoma, which is characterized by inverted polarity. Aberrant activation of RHO–ROCK signaling plays a critical role in the MPC phenotype. Establishing in vitro models will contribute to future drug targeting of the abnormal polarity status in cancer.

Analysis of the Influencing Factors of Sentinel Lymph Node Metastasis in Breast Cancer

Objective

To analyze and discuss the influencing factors of sentinel lymph node metastasis in breast cancer.

Methods

A total of 469 breast cancer patients admitted in the Department of Pathology of Guangdong Women and Children Hospital from October 2016 to December 2021 were retrospectively analyzed. The general information, immunohistochemical expression, tumor molecular subtype, tumor size, histological grade, pathological type, and tumor location were collected and the relationship with sentinel lymph node metastasis was analyzed.

Results

For patients with different age, Ki-67 and Human epidermal growth factor receptor-2 (HER-2) immunohistochemical expression level (invasive cancer), molecular subtype (invasive cancer), tumor size, histological grade (invasive cancer) and pathological type. The results of multivariate logistic regression analysis showed that the age was less than or equal to 40 years; the molecular subtype was Luminal B and HER-2 overexpression (invasive cancer); tumor was larger; the histological grade (invasive cancer) was higher; the pathological type was invasive carcinoma, there were independent risk factors for sentinel lymph node metastasis in breast cancer. The sentinel lymph node metastasis rates of invasive lobular carcinoma, invasive micropapillary carcinoma, and metaplastic carcinoma (all met the criteria for squamous cell carcinoma and histological grade III) were higher than 50% in special invasive carcinomas.

Conclusion

Age, expression level of Ki 67 and HER-2, molecular typing, tumor volume and histological grade are all high-risk factors related to sentinel lymph node metastasis of breast cancer. When one or more of the above factors are involved in an examination, pathologists should be more cautious in making a sentinel lymph node frozen diagnosis. By standardizing the sampling and increasing the number of frozen sections (slicing more frozen tissue layers), the section quality can be improved. This may be conducive to reducing the false negative rate and reducing the pain and risk of secondary surgery.

Evaluation of Lymph Node Metastasis in Invasive Micropapillary Breast Carcinoma and Other Its Related Variables

Background: The rate of lymph node metastasis in patients with invasive micropapillary carcinoma (IMPC) could be considered a critical prognostic factor whose measurement may enhance therapeutic outcomes in these patients. Objectives: The current study aims at determining the rate of lymph node involvement in IMPC patients and comparing it with that of invasive ductal carcinoma, not otherwise specified (IDC-NOS) patients. Methods: In this case-control study, a total of 124 participated, including 61 patients with IMPC and 63 patients with IDC-NOS. The rate of lymph node metastasis and its possible connection with the patient's age, tumor size, grade and focality, lymphovascular invasion, and proportion of micropapillary component were determined in patients with IMPC and compared to that of IDC-NOS patients. Results: Lymph node involvement was detected in 80.3% of patients with IMPC, which is significantly higher compared to patients with IDC-NOS. No significant correlation was found between lymph node metastasis and the patients’ age, tumor size, and focality in both IMPC and IDC-NOS groups. Furthermore, no significant relationship was observed between lymph node metastasis and tumor grade in IMPC, while metastasis to lymph nodes was directly correlated with higher tumor grades of NOS type. Moreover, in both types of cancer, lymph node metastasis was significantly associated with lymphovascular invasion. In patients with IMPC, no statistically significant relevance was observed between lymph node metastasis and the percentage of micropapillary components. Conclusions: According to the results of this study, patients with IMPC had a significantly higher rate of lymph node involvement compared to IDC-NOS. Hence, the rate of lymph node involvement could be used as a prognostic factor in these patients.

Micropapillary Breast Carcinoma: From Molecular Pathogenesis to Prognosis

Invasive micropapillary carcinoma (IMPC) of the breast is an infrequent type of breast cancer often discussed for its potency for lymphovascular invasion and difficulty in accurate imaging estimation. Micropapillary carcinomas are noted to be present as larger tumors, of higher histological grade and a notably higher percentage of disease-positive lymph nodes. Hormonal and HER-2 positivity in IMPC is also commoner when compared to other NST carcinomas. IMPC occurs either as a pure form or more often as a component of mixed Non-Specific Type (NST) carcinoma. The latest data suggest that despite having comparable survival rates to other histological subtypes of breast carcinoma, effective surgical treatment often requires extended surgical margins and vigilant preoperative axillary staging due to an increased incidence of lymph node invasion, and locoregional recurrence. Moreover, the presence of micropapillary in situ components within tumors also seems to alter tumor aggression and influence the nodal disease stage. In this review, we present an overview of the current literature of micropapillary carcinoma of the breast from biology to prognosis, focusing on biological differences and treatment.

A rare case of invasive micropapillary carcinoma of the breast

Invasive micropapillary carcinoma (IMPC) is a rare, distinct histological subtype of breast carcinoma. While micropapillary histological architecture is found in up to 2-8% of all breast cancers, pure micropapillary carcinoma is infrequent and comprises 0.9-2% of breast carcinomas. Invasive micropapillary carcinoma is emerging as an oncological and surgical challenge due to a plethora of characteristics that constitute this histological pattern - interestingly, both elusive and aggressive. We present the case of a woman presenting with IMPC, who was primarily treated with tumour and lymph node marking, followed by primary systemic therapy (PST), and consequent oncoplastic surgery with sentinel lymph node biopsy. Our case report outlines the importance of awareness of histological subtypes in breast cancer by focusing on a case report of IMPC. The breast surgeon must be aware of the lymphotropic behaviour of this subtype and the high prevalence of lymph node involvement in such patients, and therefore focus on rigorous axillary assessment. One must not forget that, despite having a more aggressive biological profile, IMPC has demonstrated no difference in survival when compared to other histological subtypes, and treatment should conform to international guidelines with an emphasis on nodal staging.

Spatial transcriptomics reveals gene expression characteristics in invasive micropapillary carcinoma of the breast

Invasive micropapillary carcinoma (IMPC) is a special histological subtype of breast cancer, featured with extremely high rates of lymphovascular invasion and lymph node metastasis. Based on a previous series of studies, our team proposed the hypothesis of "clustered metastasis of IMPC tumor cells". However, the transcriptomics characteristics underlying its metastasis are unknown, especially in spatial transcriptomics (ST). In this paper, we perform ST sequencing on four freshly frozen IMPC samples. We draw the transcriptomic maps of IMPC for the first time and reveal its extensive heterogeneity, associated with metabolic reprogramming. We also find that IMPC subpopulations with abnormal metabolism are arranged in different spatial areas, and higher levels of lipid metabolism are observed in all IMPC hierarchical clusters. Moreover, we find that the stromal regions show varieties of gene expression programs, and this difference depends on their distance from IMPC regions. Furthermore, a total of seven IMPC hierarchical clusters of four samples share a common higher expression level of the SREBF1 gene. Immunohistochemistry results further show that high SREBF1 protein expression is associated with lymph node metastasis and poor survival in IMPC patients. Together, these findings provide a valuable resource for exploring the inter- and intra-tumoral heterogeneity of IMPC and identify a new marker, SREBF1, which may facilitate accurate diagnosis and treatment of this disease.

Survival Outcomes After Breast-Conserving Therapy Compared With Mastectomy for Patients With Early-Stage Invasive Micropapillary Carcinoma of the Breast: A SEER Population-Based Study

Background

Invasive micropapillary breast carcinoma (IMPC) is a relatively rare pathological type of invasive breast cancer. Little is currently known on the efficacy and safety of breast-conserving treatment (BCT, lumpectomy plus postsurgical radiation) compared with mastectomy in women diagnosed with early-stage IMPC. Accordingly, we sought to investigate the long-term prognostic differences between BCT and mastectomy in patients with T1-3N0-3M0 invasive micropapillary breast carcinoma using data from the Surveillance, Epidemiology, and End Results (SEER) database.

Materials and Methods

We retrospectively analyzed 1,203 female patients diagnosed with early-stage IMPC between 2004 and 2015 from the SEER database. The impact of different surgical approaches on patient prognosis was assessed by the Kaplan-Meier method and Cox proportional risk models.

Results

A total of 609 and 594 patients underwent mastectomy and BCT, respectively. Compared with patients who underwent a mastectomy, patients in the BCT group were older and had lower tumor diameters, lower rates of lymph nodes metastasis, and higher rates of ER receptor positivity and PR receptor positivity (p < 0.05). Kaplan-Meier plots showed that the overall survival (OS) and breast cancer-specific survival (BCSS) were higher in the BCT group than in the mastectomy group. In subgroup analysis, patients with T2 stage in the BCT group had better OS than the mastectomy group. Multivariate analysis showed no statistical difference in OS and BCSS for patients in the mastectomy group compared with the BCT group (hazard ratio (HR) = 0.727; 95% confidence interval (95% CI) 0.369–1.432, p = 0.357; HR = 0.762; 95% CI 0.302–1.923, p = 0.565; respectively). During the multivariate analysis and stratifying for the T stage, a better OS was found for patients with T2 stage in the BCT group than the mastectomy group (HR = 0.333, 95% CI: 0.149–0.741, p = 0.007). There was no significant difference in OS for patients with T1 and T3 stages between the BCT and mastectomy groups (p > 0.05).

Conclusion

In women with early-stage IMPC, BCT was at least equivalent to mastectomy in terms of survival outcomes. When both procedures are feasible, BCT should be recommended as the standard surgical treatment, especially for patients with T2 disease.

The Expression of Galectin-3 in Tumor and Cancer-Associated Fibroblasts in Invasive Micropapillary Breast Carcinomas: Relationship with Clinicopathologic Parameters

Objective

Galectin-3 affects tumor progression and cell surface polarization by expressing from the tumor and cancer-associated fibroblasts (CAFs). Therefore, it may have a role on micropapillary carcinomas (IMPC), which have characteristic morphological features. The aim was to investigate the expression levels of Galectin-3 within tumor and peritumoral CAFs in IMPC, and to compare with expression in invasive ductal carcinomas (IDC).

Materials and Methods

Hematoxylin and Eosin-stained preparations of resection materials examined between 2010-2016 were re-evaluated. Thirty-four IMPC cases and 34 IDC cases with similar molecular subtype distribution to IMPC were compared. Galectin-3 levels were evaluated with a calculated H-score in tumor and semi-quantitatively in CAFs.

Results

While tumoral Galectin-3 expression levels were higher in IMPCs compared to IDCs, there was no difference for Galectin-3 expression in CAFs between the two histologic types. However, there was no significant relationship between tumoral Galectin-3 expression and clinicopathological parameters in IMPCs. When the subjects were divided into two groups, depending on their Galectin-3 status regardless of histological types, the loss of Galectin-3 expression in tumor was found to be related to larger tumor size/advanced pT stage and a greater number of metastatic nodes. Additionally, expression of Galectin-3 in CAFs was found to be associated with distant metastasis.

Conclusion

IMPC showed prominent Galectin-3 expression in tumor compared to IDC. However, independent from the histological type, whereas the loss of Galectin-3 expression in tumor showed an association with larger tumor size and higher number of metastatic axillary lymph nodes, the presence of Galectin-3 expression in CAFs showed an association with distant metastasis.

Crosstalks Among Cancer Stem Cells and Histopathologic Features in Determining Prognosis in Canine Mammary Gland Carcinomas

The purpose of the present work was the evaluation of the prognostic potential of histopathologic features, cancer stem cells (CSCs), and epthelial-mesenchymal transition (EMT) in relation to lymph node status and lymphovascular invasion (LVI) in canine mammary gland carcinomas (CMGCs). CSCs are proposed as the main cause of tumorigenesis, therapy failure, and recurrence which form a small fraction of tumor bulk. We evaluated presence of micropapillary growth pattern (MGP), infiltration into surrounding tissues (IST), and vasculogenic mimicry (VM) in H&E stained slides of 26 paraffin-embedded tumor samples. Lymph nodes of all cases were assessed. Additionally, they were examined immunohistochemically in terms of vimentin expression as an indicator of EMT which is a well-known mechanism for metastasis, and CD44, CD24, and ALDH1 for CSCs detection. Data analyses showed significant relationships between MGP and CSCs (P = 0.037), VM and CSCs (P = 0.013), lymph node status and CSCs (P = 0.0001), lymph node status and EMT (P = 0.003), IST and LVI (P = 0.05), VM and LVI (P = 0.01), VM and lymph node status (P = 0.007), and LVI and lymph node status (P = 0.04). Results indicated the prognostic value of MGP, VM, and CSCs with respect to confirmed prognostic markers, including LVI and lymph node involvement, in CMGCs.

Aberrant activation of Rho/ROCK signaling in impaired polarity switching of colorectal micropapillary carcinoma

Micropapillary carcinoma (MPC) is a morphologically distinctive form of carcinoma, composed of small nests of cancer cells surrounded by lacunar spaces. Invasive MPC is associated with poor prognosis. The nests of tumor cells in MPC reportedly exhibit reverse polarity, although the molecular mechanisms underlying MPC patterns are poorly understood. Using the cancer tissue-originated spheroid (CTOS) method, we previously reported polarity switching in colorectal cancer (CRC). When cultured in suspension, the apical membrane promptly switches from the outside surface of the CTOSs to the surface of the lumen inside the CTOSs under extracellular matrix (ECM)-embedded conditions, and vice versa. Here, we investigated two CTOS lines from CRC patient tumors with MPC lesions. Xenograft tumors from the CTOSs exhibited the MPC phenotype. The MPC-CTOSs did not switch polarity in vitro. Time-course analysis of polarity switching using real-time imaging of the apical membrane revealed that local switching was continually propagated in non-MPC-CTOSs, while MPC-CTOSs were unable to complete the process. Integrin β4 translocated to the outer membrane when embedded in ECM in both MPC and non-MPC-CTOSs. Protein levels, as well as the active form of RhoA, were higher in MPC-CTOSs. The suppression of RhoA activity by GAP overexpression enabled MPC-CTOSs to complete polarity switching both in vitro and in vivo, while overexpression of active RhoA did not affect polarity switching in non-MPC-CTOSs. Pretreatment with a ROCK inhibitor enabled MPC-CTOSs to complete polarity switching both in vitro and in vivo, although delayed treatment after becoming embedded in ECM failed to do so. Thus, the inability to switch polarity might be a cause of MPC, in which the aberrant activation of RhoA plays a critical role. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Clinicopathological characteristics of pancreatic ductal adenocarcinoma with invasive micropapillary carcinoma component with emphasis on the usefulness of PKCζ immunostaining for detection of reverse polarity

Invasive micropapillary carcinoma (IMPC) is a rare distinct histopathological subtype, characterized by the presence of carcinoma cells displaying reverse polarity. Only limited clinicopathological information is available regarding pancreatic IMPC. The aim of the present study was to clarify the clinicopathological features of pancreatic IMPC and the usefulness of protein kinase C (PKC)ζ immunostaining for the detection of reverse polarity. We reviewed 242 consecutive surgically resected specimens of pancreatic ductal adenocarcinoma and selected samples with an IMPC component. Clinicopathological characteristics were compared between the IMPC and non-IMPC groups. Immunohistochemical staining for PKCζ was performed using an autostainer. In total, 14 cases had an IMPC component (5.8%). The extent of IMPC component ranged from 5 to 20%. There were no significant differences in tumor location, T category, lymph node metastatic status, preoperative carbohydrate antigen 19-9 level, resection status and overall survival between the IMPC and non-IMPC groups. Immunostaining for PKCζ clearly showed reverse polarity of the neoplastic cells of IMPC. Although previous reports have shown that the presence of an IMPC component (>20% of the tumor) indicated poor prognosis, the present study demonstrated that presence of IMPC <20% did not suggest a worse prognosis.

Novel Histologic Classification of Small Tumor Cell Nests for Lung Adenocarcinoma With Prognostic and Etiological Significance: Small Solid Nests and Pure Micropapillary Nests

Small tumor cell nests such as micropapillary nests are histologic poor prognostic markers for adenocarcinomas of various organs, including the lung. However, for the lung, the association of micropapillary patterns with smoking is controversial, which may be because of a vague definition of micropapillary patterns. This study clarifies the implications of small tumor cell nests by introducing a new dichotomic classification based on the glandular polarity of tumor cells: pure micropapillary nests (pMPs), preserving glandular polarity, and small solid nests (SSNs), lacking polarity. We examined the clinicopathologic factors in 436 resected adenocarcinomas, and analyzed the overall survival between groups classified by either the presence or absence of pMPs and SSNs. pMP was positively associated with nonsmoking-related features such as epidermal growth factor receptor mutations and thyroid transcription factor 1 expression. By contrast, SSN was positively associated with smoking-related features such as KRAS mutations and hepatocyte nuclear factor-4a expressions. Besides, pMP and SSN were significant and independent indicators of poor prognosis in all stages. SSN was an indicator in stage I too, whereas pMP was not. Furthermore, prognoses of the group with SSN were significantly worse than those of pMP-only group. In conclusion, the present study has revealed 2 completely different patterns of small tumor cell nests in lung adenocarcinoma, the nonsmoking-related pMPs, and the smoking-related SSNs, by considering glandular polarity. MPP should include only pMPs, and SSNs should be in a solid pattern. This novel classification might boast clinical significance as a potent poor prognostic marker as well as a factor reflecting etiological and genetic characters.

sLex expression in invasive micropapillary breast carcinoma is associated with poor prognosis and can be combined with MUC1/EMA as a supplementary diagnostic indicator

OBJECTIVE

Mucin 1 (MUC1/EMA) and sialyl Lewis X (sLex) indicate polarity reversal in invasive micropapillary carcinoma (IMPC). The purpose of this study was to evaluate the expression of MUC1/EMA and sLex and to assess their diagnostic and prognostic value in patients with IMPC.

METHODS

The expression of sLex and MUC1/EMA in 100 patients with IMPC and a control group of 89 patients with invasive ductal carcinoma not otherwise specified (IDC-NOS) were analyzed with IHC. Fresh tumor tissues were collected from patients with IMPC or IDC-NOS for primary culture and immunofluorescence analysis.

RESULTS

The rate of nodal metastasis was higher in patients with IMPC than those with IDC-NOS, and IMPC cells tended to express more sLex and MUC1/EMA in the cytomembranes (the stroma-facing surfaces of the micropapillary clusters) than IDC-NOS cells. In IMPC, high cytomembrane expression of sLex, but not MUC1/EMA, indicated poor prognosis. In addition, among the 100 patients with IMPC, 10 patients had sLex+/EMA- expression patterns, and 8 patients had sLex-/EMA+ expression patterns. The primary IMPC cells were suspended, non-adherent tumor cell clusters, whereas the primary IDC cells were adherent tumor cells. Immunofluorescence analysis showed that MUC1/EMA and sLex were co-expressed on the cytomembranes in IMPC cell clusters and in the cytoplasm in IDC-NOS cells.

CONCLUSIONS

sLex can be used as a prognostic indicator and can be combined with MUC1/EMA as a complementary diagnostic indicator to avoid missed IMPC diagnosis.

Characterization of neoplastic cells outlining the cystic space of invasive micropapillary carcinoma of the canine mammary gland

BACKGROUND

Invasive micropapillary carcinoma (IMPC) is a rare malignant breast tumor and a variant form of invasive ductal carcinoma that is an aggressive neoplasm of the human breast and canine mammary gland. The importance of the tumor microenvironment in cancer development has gradually been recognized, but little is known about the cell types outlining the cystic space of canine IMPC. This study aimed to characterize the neoplastic cells outlining the cystic space of IMPC.

RESULTS

Immunohistochemistry (IHC), immunofluorescence (IF), superresolution and transmission electron microscopy (TEM) were used to assess the cell types in the cystic areas of IMPCs. Cells expressing the mesenchymal markers alpha-smooth muscle actin (αSMA), Vimentin, and S100A4 outlined the cystic space of IMPC. Furthermore, loss of epithelial cell polarity in IMPC was shown by the localization of MUC1 at the stroma-facing surface. This protein modulates lumen formation and inhibits the cell-stroma interaction. Immunohistochemical and IF staining for the myoepithelial cell marker p63 were negative in IMPC samples. Furthermore, associated with peculiar morphology, such as thin cytoplasmic extensions outlining cystic spaces, was observed under TEM. These observations suggested cells with characteristics of myoepithelial-like cells.

CONCLUSIONS

The cells outlining the cystic space of IMPC in the canine mammary gland were characterized using IHC, IF and TEM. The presence of cells expressing αSMA, Vimentin, and S100A4 in the IMPC stroma suggested a role for tumor-associated fibroblasts in the IMPC microenvironment. The reversal of cell polarity revealed by the limited basal localization of MUC1 may be an important factor contributing to the invasiveness of IMPC. For the first time, the cystic space of canine mammary gland IMPC was shown to be delimited by myoepithelial-like cells that had lost p63 expression. These findings may enhance our understanding of the cellular microenvironment of invasive tumors to improve cancer diagnosis and treatment.

Rare Breast Cancer Subtypes

PURPOSE OF REVIEW

Breast cancer is a collection of diseases including the more common invasive ductal and lobular carcinomas and rarer subtypes of breast cancer. This review summarizes the features of rare breast cancers.

RECENT FINDINGS

Each of the rare tumors has defined pathological and clinical features that impact treatment recommendations. In this review, we summarize these for each rare type of breast cancer and where available we include molecular features of each tumor. Rare subtypes of breast cancer each have unique features. In many cases, data is limited for the optimal treatment approaches.

Nomogram Predicting the Risk of Locoregional Recurrence After Mastectomy for Invasive Micropapillary Carcinoma of the Breast

BACKGROUND

The risk of locoregional recurrence (LRR) after mastectomy for breast invasive micropapillary carcinoma (IMPC) remains poorly defined. We aimed to construct an effective prognostic nomogram to estimate the individualized risk of LRR for providing accurate information for long-term follow-up.

PATIENTS AND METHODS

A total of 388 patients with breast IMPC were included in the current study. Based on the Cox regression and clinical significance, a nomogram with an online prediction version was created. This model was evaluated and internally validated by concordance index and calibration plot. Receiver operating characteristic curve and decision curve analysis were used to assess the discrimination and clinical utility, and Kaplan-Meier curves estimated the probability of LRR.

RESULTS

The variables (age, lymph node metastasis, hormone receptor status, lymphovascular invasion, histologic grade, and adjuvant radiotherapy) were included in the nomogram. This model was well-calibrated to predict the possibility of LRR and displayed favorable clinical utility; the concordance index was 0.86 (95% confidence interval, 0.81-0.91), which was higher than any single predictor. The area under the curve of the nomogram was 0.89, whereas that of the conventional staging system was 0.72. An online prognostic nomogram was built for convenient use. Kaplan-Meier curves showed that the nomogram had a better risk stratification than the conventional staging system.

CONCLUSIONS

The nomogram could accurately predict the individualized risk of LRR after mastectomy for breast IMPC. By identifying the risk stratification, this model is expected to assist clinicians and patients in improving long-term follow-up strategies.

Invasive Micropapillary Carcinoma of the Uterine Cervix

We herein present a case of uterine cervical invasive micropapillary carcinoma (IMPC) in a 35-year-old woman. She had neither specific symptoms nor any previous gynecological history. A cervical punch biopsy revealed a high-grade squamous intraepithelial lesion and concurrent intestinal-type mucinous carcinoma. Based on the preoperative diagnosis of endocervical adenocarcinoma, she underwent radical hysterectomy with bilateral salpingo-oophorectomy and bilateral pelvic lymph node dissection. Grossly, there was an ovoid, slightly elevated mass with surface nodularity in the lower endocervix, measuring 10 × 8 mm. Histologically, the tumor consisted predominantly of tufts of tumor cells arranged in micropapillary structures devoid of fibrovascular cores and surrounded by clear, empty, lacunar spaces between tumor cell nests and stroma. The IMPC component comprised 90% of the entire tumor volume. The greatest dimension and stromal invasion depth of the IMPC were 8 and 3 mm, respectively (FIGO stage IA2). Immunostaining revealed that mucin 1 (MUC1) surrounded each micropapillary structure, indicating the reverse epithelial polarity of the glandular cells. MUC1 was localized predominantly in the stroma-facing surface of the cell clusters, accentuating the outlines of the micropapillary structures by forming a distinct, characteristic band on this surface. In addition, targeted sequencing analysis of the IMPC revealed a missense PIK3CA mutation (c.1633G>A). In summary, we present the clinicopathological characteristics of cervical IMPC. We demonstrate for the first time that IMPC of the uterine cervix harbors a pathogenic missense mutation in PIK3CA. Further investigations using larger cohorts of patients are necessary to confirm these findings.

Papillary lesions of the breast: a review

Papillary breast lesions are rare breast tumors that comprise a broad spectrum of diseases. Pathologically they present as mass-like projections attached to the wall of the ducts, supported by fibrovascular stalks lined by epithelial cells. On mammogram they appear as masses that can be associated with microcalcifications. Ultrasound is the most used imaging modality. On ultrasound papillary lesions appear as homogeneous solid lesions or complex intracystic lesions. A nonparallel orientation, an echogenic halo or posterior acoustic enhancement associated with microcalcifications are highly suggestive of malignancy. MRI has proven to be useful to establish the extent of the lesion. Core needle biopsy is the gold standard for diagnosis. Surgical excision is usually recommended, although treatment for papillomas without atypia is still controversial.

Villin is a biomarker for reverse polarity in colorectal micropapillary carcinoma

Colorectal cancer (CRC) is a common malignant tumor of digestive system. CRC with micropapillary pattern (MPP) is an aggressive variant of colorectal adenocarcinoma. The aim of the present study was to clarify the clinicopathological significance and the prognostic role of an immunohistochemical marker, MPP, in CRC. The association between MPP and clinicopathological characteristics and prognosis in 286 cases of CRC (286/453 cases had follow-up information) were analysed. Then, 81 tissues without MPP and 90 tissues with MPP were analysed by immunohistochemistry using antibodies against villin, E-cadherin and epithelial membrane antigen (EMA). Bioinformatics was used to evaluate the expression of these three indicators in CRC. The proportion of micropapillary carcinoma in the overall tumour was ≥5%, and was observed in 90/453 cases (19.8%). The present data showed that CRC with MPP displayed higher rates of vascular and lymphatic invasion, a higher metastatic lymph node ratio and a higher pathological tumour and metastasis stage compared with CRC without MPP. The positive expression rates of EMA, E-cadherin and villin were 50.3, 93.4 and 96.5%, respectively. In 90 CRC cases with MPP, EMA inside-out pattern (I/OP) staining was observed in 26 cases (28.9%), and it was often focal and partial, while 37 cases (41.1%) had E-cadherin focal and partial staining compatible with reverse polarity. Villin I/OP staining was observed in 77 cases (85.6%), and circumferential staining predominated over partial staining. Overall, the data suggested that the presence of MPP is significantly associated with aggressive tumour behaviour and worse overall survival rate in CRC. Visualization and distinction of reverse polarity of colorectal micropapillary carcinomas is improved villin compared with EMA or E-cadherin.