Prognostic significance of tumor grading and staging in mammary carcinomas with neuroendocrine differentiation

Targeting the "tumor microenvironment": RNA-binding proteins in the spotlight in colorectal cancer therapy

Colorectal cancer (CRC) is the third most common cancer and has the second highest mortality rate among cancers. The development of CRC involves both genetic and epigenetic abnormalities, and recent research has focused on exploring the ex-transcriptome, particularly post-transcriptional modifications. RNA-binding proteins (RBPs) are emerging epigenetic regulators that play crucial roles in post-transcriptional events. Dysregulation of RBPs can result in aberrant expression of downstream target genes, thereby affecting the progression of colorectal tumors and the prognosis of patients. Recent studies have shown that RBPs can influence CRC pathogenesis and progression by regulating various components of the tumor microenvironment (TME). Although previous research on RBPs has primarily focused on their direct regulation of colorectal tumor development, their involvement in the remodeling of the TME has not been systematically reported. This review aims to highlight the significant role of RBPs in the intricate interactions within the CRC tumor microenvironment, including tumor immune microenvironment, inflammatory microenvironment, extracellular matrix, tumor vasculature, and CRC cancer stem cells. We also highlight several compounds under investigation for RBP-TME-based treatment of CRC, including small molecule inhibitors such as antisense oligonucleotides (ASOs), siRNAs, agonists, gene manipulation, and tumor vaccines. The insights gained from this review may lead to the development of RBP-based targeted novel therapeutic strategies aimed at modulating the TME, potentially inhibiting the progression and metastasis of CRC.

Neuroendocrine tumor of the breast showing invasive micropapillary features and multiple lymph node metastases

BACKGROUND

Herein, for the first time, we present a case with mixed invasive micropapillary and neuroendocrine mammary neoplasm.

CASE

The patient, a 65-year-old postmenopausal woman, had become aware of a tumor in her right breast 11 months prior to presentation at our hospital. The cut surface of the mastectomy specimen contained a well-circumscribed, multinodular, red-brown tumor, measuring 15x15x15 cm. Histopathologically, this solid cystic lesion consisted of medullary growth of cancer cells accompanied by a well-developed vascular network as well as conspicuous hemorrhage. Cancer cell nests of various sizes displayed an "inside-out" structure surrounded by empty spaces. Most cancer cells were polygonal, though a few were short fusiform-shaped, and possessed finely granular, eosinophilic cytoplasm and ovoid, fine-granular nuclei. Eighteen mitotic figures were observed in 10 high-power fields. Macrometastases, up to 13x8 mm in size, with the same morphological features as the original tumor site, were identified in 3 of 15 dissected right axillary nodes. Immunohistochemically, primary and metastatic cancer cells were diffusely positive for chromogranin A and the estrogen receptor (Allred's total score: 8) and focally reactive for synaptophysin and the progesterone receptor (total score: 5). HER2 and cytokeratin 5/6 were negative, and the MIB-1 labelling index was 36.2%. MUC1 and EMA lined the stroma-facing surfaces of the cell membranes, indicating reversed polarity.

CONCLUSION

Our current patient, who had an invasive breast carcinoma with concomitant neuroendocrine and micropapillary features, developed multiple nodal metastases in association with a large-diameter tumor showing a luminal B-like immuno-profile. Accordingly, meticulous clinical follow-up remains essential for this uncommon case.

Comparison of the mutational profiles of neuroendocrine breast tumours, invasive ductal carcinomas and pancreatic neuroendocrine carcinomas

The pathophysiology and the optimal treatment of breast neuroendocrine tumours (NETs) are unknown. We compared the mutational profiles of breast NETs (n = 53) with those of 724 publicly available invasive ductal carcinoma (IDC) and 98 pancreatic NET (PNET) cases. The only significantly different pathogenetic or unknown variant rate between breast NETs and IDCs was detected in the TP53 (11.3% in breast NETs and 41% in IDCs, adjusted p value 0.027) and ADCK2 (9.4% in breast NETs vs. 0.28% in IDCs, adjusted p value 0.045) genes. Between breast NETs and PNETs, different pathogenetic or unknown variant frequencies were detected in 30 genes. For example, MEN1 was mutated in only 6% of breast NETs and 37% in PNETs (adjusted p value 0.00050), and GATA3 pathogenetic or unknown variants were only found in 17.0% of breast NETs and 0% in PNETs (adjusted p value 0.0010). The most commonly affected oncogenic pathways in the breast NET cases were PI3K/Akt/mTOR, NOTCH and RTK-RAS pathways. Breast NETs had typically clock-like mutational signatures and signatures associated with defective DNA mismatch repair in their mutational landscape. Our results suggest that the breast NET mutational profile more closely resembles that of IDCs than that of PNETs. These results also revealed several potentially druggable targets, such as MMRd, in breast NETs. In conclusion, breast NETs are indeed a separate breast cancer entity, but their optimal treatment remains to be elucidated.

Expression of novel neuroendocrine markers in breast carcinomas: a study of INSM1, ASCL1, and POU2F3

INSM1, ASCL1, and POU2F3 are novel transcription factors involved in neuroendocrine (NE) differentiation of neoplasms in several organs, but data on their expression in breast carcinomas (BCs) are limited. We retrospectively evaluated the expression of these markers in a series of 97 BCs (58 with NE morphology and 39 with otherwise uncommon morphology) tested prospectively using immunohistochemistry (IHC). Nuclear staining in >50% of the cells was used as the positive cut-off. Thirty-two of the 97 BCs (33%) were INSM1-positive. INSM1-positivity correlated significantly with histologic type and presence of stromal mucin. INSM1 also correlated with synaptophysin and chromogranin, established markers of NE differentiation (P < .0001 and P = .0023, respectively). In BC with NE morphology, the expression of INSM1 supported NE differentiation, and INSM1 was more specific than synaptophysin and more sensitive and specific than chromogranin. INSM1 was the most expressed NE marker in 17 BCs. INSM1-positive BCs included 56% of solid papillary BCs, 88% of BCs with solid papillary features, and 75% of high-grade NE carcinomas. Of 35 BCs tested for POU2F3 and ASCL1, only 1 and 4 cases were positive, respectively. Our results show that INSM1 is a sensitive marker of NE differentiation in BC and should be included with synaptophysin and chromogranin in the IHC panel used to evaluate NE differentiation in BC with NE morphology. ASCL1 and POU2F3 are uncommon in BC and their routine assessment is not warranted.

A high-quality model for predicting the prognosis of breast neuroendocrine carcinoma to help clinicians decide on appropriate treatment methods: A population-based analysis

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The incidence of breast neuroendocrine carcinoma (NEC) was approximately 1.96–2.37%.

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Breast NEC had poor prognosis than breast invasive ductal carcinoma (IDC).

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Patients with breast NEC may benefit from surgery plus chemotherapy.

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Efficient models were constructed to guide the treatment of breast NEC.

Background

Breast neuroendocrine carcinoma (NEC) is a rare malignancy with unclear treatment options and prognoses. This study aimed to construct a high-quality model to predict overall survival (OS) and breast cancer-specific survival (BCSS) and help clinicians choose appropriate breast NEC treatments.

Patients and methods

A total of 378 patients with breast NEC and 349,736 patients with breast invasive ductal carcinoma (IDC) were enrolled in the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2018. Propensity score matching (PSM) was performed to balance the clinical baseline. Prognostic factors determined by multivariate Cox analysis were included in the nomogram. C-index and calibration curves were used to verify the performance of the nomogram.

Results

Nomograms were constructed for the breast NEC and breast IDC groups after PSM. The C–index of the nomograms ranged from 0.834 to 0.880 in the internal validation and 0.818–0.876 in the external validation, indicating that the nomogram had good discrimination. The risk stratification system showed that patients with breast NEC had worse prognoses than those with breast IDC in the low-risk and intermediate-risk groups but had a similar prognosis that those in the high-risk group. Moreover, patients with breast NEC may have a better prognosis when undergoing surgery plus chemotherapy than when undergoing surgery alone or chemotherapy alone.

Conclusions

We established nomograms with a risk stratification system to predict OS and BCSS in patients with breast NEC. This model could help clinicians evaluate prognosis and provide individualized treatment recommendations for patients with breast NEC.

The Effect of the Extent of Neuroendocrine Differentiation on Cytopathological Findings in Primary Neuroendocrine Neoplasms of the Breast

Objective:

This study aimed to describe the cytological features of neuroendocrine breast tumors and to show the effect of the extent of neuroendocrine differentiation on cytological features.

Methods:

Breast tumor excision materials showing immunostaining with neuroendocrine markers (Synaptophysin or Chromogranin A) were determined and divided into two groups: cases with focal (10%–50% of tumor cells) staining and cases with diffuse (>50% of tumor cells) staining. A group of cases without neuroendocrine features/staining was used as control group. Fine needle aspiration biopsy specimens of the tumor mass or metastatic lymph nodes were examined and compared.

Results:

Twenty cases with neuroendocrine differentiation were included. Eleven cases were in the diffuse group, nine cases were in the focal group. Clean background, high cellularity, loosely cohesive cell groups with monotonous appearance, and naked nuclei were more common in the diffuse group. On the contrary, tight cohesive cell groups, the proportion of large cells, nuclear pleomorphism, and nucleolar prominence were higher in the group with focal staining. Plasmocytoid appearance, isolated cell groups, and binucleation were in similar distribution in both groups. Although round-oval nuclei were dominant in both groups, round nuclei were observed to be slightly more in the diffuse group. Only two cases in diffuse group showed cytoplasmic granularity and one case in focal group showed necrosis and mitosis. In the control group, tight cohesive groups, large cell size, pleomorphism, prominent nucleoli, and coarse chromatin were more commonly encountered.

Conclusions:

Clean background, hypercellularity, loss of cohesion, naked nuclei, monotonous cells with round nucleus, and granular cytoplasm were more prominent in cases showing diffuse staining with neuroendocrine markers. Suspecting neuroendocrine differentiation in tumors that show focal staining with neuroendocrine markers can be challenging in cytological preparations.

Neuroendocrine Neoplasms of the Breast: The Latest WHO Classification and Review of the Literature

Simple Summary

Breast tumors exhibiting neuroendocrine differentiation are a heterogeneous group of tumors that have been variously defined in previous World Health Organization (WHO) classifications. In the WHO Classification of Tumours, 5th edition, neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs) of the breast, both of which are invasive cancers, are classified as neuroendocrine neoplasms (NENs) of the breast. However, the clinical significance of NE differentiation in breast cancers, especially in NETs of the breast, is not yet fully understood, and a large overlap appears to exist between breast cancers showing NE differentiation and invasive breast cancer of no special type (IBC-NST). While breast NECs show distinct clinical and morphological features, diagnosis of NETs based on the morphological characteristics alone can be challenging; one reason is that breast NETs do not necessarily have the same morphological characteristics as those of NENs arising in other organs. Thus, the heterogeneity of breast tumors with neuroendocrine differentiation and the changes in their classifications over the years have left many open issues that still need to be resolved. In this review, we shall summarize the history of breast “NENs,” including of mixed types of tumors and the characteristics of these tumors, and discuss their differences from NENs arising in other organs.

Abstract

Breast tumors with neuroendocrine (NE) differentiation comprise an uncommon and heterogeneous group of tumors, including invasive breast cancer of no special type (IBC-NST) with NE features, neuroendocrine tumors (NETs), and neuroendocrine carcinoma (NEC). The most recent World Health Organization (WHO) classification in 2019 defined neuroendocrine neoplasms (NENs) of the breast (Br-NENs) as tumors in which >90% of cells show histological evidence of NE differentiation, including NETs (low-grade tumors) and NEC (high-grade). Due to the low prevalence of these tumors and successive changes in their diagnostic criteria over the years, only limited evidence of these tumors exists, derived mainly from case reports and retrospective case series. Breast tumors with NE differentiation are usually treated like the more commonly occurring IBC-NSTs. Immunohistochemistry (IHC) of breast tumors with NE differentiation usually shows a hormone receptor (HR)-positive and human epidermal growth factor type 2 (HER2)-negative profile, so that hormonal therapy with cyclin-dependent kinase (CDK)4/6 inhibitors or other targeted agents would be reasonable treatment options. Herein, we present a review of the literature on breast tumors with NE differentiation as defined in the latest WHO 2019 classification, and discuss the clinical management of these tumors.

Breast cancer with neuroendocrine differentiation: an update based on the latest WHO classification

Breast cancers with neuroendocrine (NE) differentiation are very heterogeneous, comprising broadly cancers that are morphologically similar to NE tumors (NET) of other anatomic sites, infiltrating breast carcinomas, no special type (IBC-NST) and other special subtypes with NE morphology and/or NE markers expression. Depending on the classification schemes, they are variably included into "NE breast cancers". The latest WHO classification harmonized NE breast cancers with NE neoplasms (NEN) of other organ systems, defined NEN into well-differentiated NET (low Nottingham grade) and poorly-differentiated NE carcinoma (NEC) (high Nottingham grade). Other IBC with NE differentiation are diagnosed based on solely the non-NEN component. Due to the changes in diagnostic criteria, variable results were obtained in the previous studies on NE breast cancers. Hence, the clinical value of NE differentiation in breast cancers is not well investigated and understood. In this review, the current understanding in the pathogenesis, clinical, prognostic, immunhistochemical, and molecular features of "NE breast cancers" is summarized. Controversial issues in their diagnosis and classification are also discussed.

Tristetraprolin, a Potential Safeguard Against Carcinoma: Role in the Tumor Microenvironment

Tristetraprolin (TTP), a well-known RNA-binding protein, primarily affects the expression of inflammation-related proteins by binding to the targeted AU-rich element in the 3' untranslated region after transcription and subsequently mediates messenger RNA decay. Recent studies have focused on the role of TTP in tumors and their related microenvironments, most of which have referred to TTP as a potential tumor suppressor involved in regulating cell proliferation, apoptosis, and metastasis of various cancers, as well as tumor immunity, inflammation, and metabolism of the microenvironment. Elevated TTP expression levels could aid the diagnosis and treatment of different cancers, improving the prognosis of patients. The aim of this review is to describe the role of TTP as a potential safeguard against carcinoma.

INSM1 is a novel prognostic neuroendocrine marker for luminal B breast cancer

Insulinoma associated protein 1 (INSM1) is a relatively new marker of neuroendocrine differentiation. It has been shown to have a high sensitivity for neuroendocrine tumours arising from different organs. This study evaluated INSM1 as a marker for neuroendocrine differentiation in infiltrating breast cancers (IBC). The expression of INSM1, together with other neuroendocrine markers (synaptophysin, chromogranin and CD56) was assessed in a large IBC cohort using tissue microarray by immunohistochemistry. Overall, 13.1%, 4.6%, 7.0% and 6.5% of the cases were positive for synaptophysin, chromogranin, INSM1 and CD56, respectively. INSM1 expression showed similar clinicopathological and biomarker profiles as chromogranin and synaptophysin. They were associated positively with luminal profile (p<0.001) and hormone receptors expression (p≤0.015), but negatively with HER2 (p≤0.044) and high molecular weight cytokeratins (p≤0.047). Using synaptophysin and/or chromogranin to define neuroendocrine differentiation, INSM1 showed a sensitivity of 37.3%, and was more sensitive than chromogranin (33.5%) and CD56 (16.4%) but less than synaptophysin (94.6%). Interestingly, INSM1 expression segregated IBC with neuroendocrine differentiation into different prognostic subgroups, particularly within luminal B subtype. Among the synaptophysin/chromogranin+ luminal B cancers, INSM1 expression was associated with significantly better survival (DFS: χ²=8.009, p=0.004; BCSS: χ²=3.873, p=0.049). Multivariate analysis showed that synaptophysin/chromogranin+ INSM1- status was an independent adverse factor for DFS (HR=2.282, 95%CI=1.196-4.356, p=0.012) in the luminal B subtype. Our data supported the usefulness of INSM1 in detecting neuroendocrine differentiation in IBC. Furthermore, INSM1 expression suggested a favourable prognostic impact; thus, it could be useful for stratifying neuroendocrine tumours with different prognosis.

Neuroendocrine breast carcinoma: a rare but challenging entity

Breast carcinoma with neuroendocrine differentiation, also known as neuroendocrine breast carcinoma (NEBC), includes a heterogeneous group of rare tumors, which account for 2–5% of all invasive breast carcinomas. Because of their low incidence, most of the current limited knowledge of these tumors derives from anecdotal case reports or small retrospective series. The diagnosis of NEBC is based on the presence of morphological features similar to gastrointestinal and lung NETs and neuroendocrine markers. NEBCs are usually hormone receptors positive and HER2 negative, but despite this luminal phenotype, most recent studies suggested that NEBC could be associated with worse prognosis compared to invasive breast cancer without neuroendocrine differentiation. Due to its rarity and lack of randomized data, there is little evidence to guide the choice of treatment, so NEBC is currently treated as any invasive breast carcinoma not-otherwise specified. Recently, attempts to molecularly characterize NEBC have been made, in order to provide new targets for a more personalized treatment of this uncommon entity.

Neuroendocrine Cancer of the Breast: A Rare Entity

Neuroendocrine breast cancer (NEBC) is a rare histotype of breast carcinoma that presents, in most cases, positive hormone receptors and negative HER2. Indeed, the analysis of gene expression profiles revealed that NEBC belongs mainly to the luminal subtype. Cases of HER2-positive and triple-negative NEBC are rare. The cardinal treatment of early NEBC is surgery, similar to the treatment of invasive non-special histological type carcinoma. The use of radiotherapy follows the criteria applied in infiltrating breast cancer of non-special histotype. In the post-operative phase, therefore after the surgical treatment of mammary quadrantectomy, or mastectomy associated with homolateral sentinel lymph node removal ± axillary dissection, based on the histopathological characteristics of the tumor, the use of chemotherapy (anthracycline + taxane) and/or hormone therapy, whether or not associated with anti-HER2 therapy (trastuzumab) is the rule. Literature data report the use of cisplatin and etoposide, as in small cell lung cancers. Most of the information currently available derive from single case reports or a series of clinical cases; it follows the difficulty of formulating definite recommendations on the correct management of this histological type of breast cancer. This review describes available knowledge on this rare entity to improve the diagnostic and therapeutic strategies and offer insights to stimulate exploration of the many aspects still unknown.

Histopathological and Clinical Differences Between Primary Breast Carcinomas With Neuroendocrine Features and Primary Breast Carcinomas Mimicking Neuroendocrine Features

We aimed to determine the histopathological differences between primary breast carcinomas with neuroendocrine features (NEBC) and carcinomas mimicking neuroendocrine features (NEBC-like). Twenty-three cases with NEBC, all showing positive staining for synaptophysin and/or chromogranin-A in ≥50% of tumor cells and 36 cases with NEBC-like (no staining for neuroendocrine [NE] markers but suspicious for NE morphology in terms of solid/trabecular growth patterns) were included in the study. Significant differences were found between the groups in terms of the patients' ages, histologic/nuclear grade of tumor, lymphovascular invasion, comedo-type ductal carcinoma in situ (DCIS), microcalcification, Ki-67 proliferation index, nuclear shape, and level of peritumoral lymphocytic infiltration. The presence of large-size solid cohesive groups of tumor cells; plasmocytoid, spindle, and/or columnar shapes of tumor cells; and eosinophilic-granular appearance of cytoplasm were mostly noted in the NEBC group. The presence of small- to medium-sized solid cohesive groups of tumor cells; high-grade histologic and nuclear features; clear cytoplasm; and round to ovoid nucleus were mostly noted in the NEBC-like group. No significant differences were found in terms of tumor size, ER/PR/HER2 status, as well as the presence of DCIS, elastosis, extracellular/intracellular mucin, signet ring cells, apocrine features, and accompanying papilloma or ductal ectasia. In conclusion, small- to medium-sized solid cohesive groups of tumor cells, high-grade features, clear cytoplasm, round to ovoid shape of nucleus, lymphovascular invasion, comedo-type DCIS, microcalcification, high level of Ki-67 proliferation index (≥20%), and moderate/strong level of peritumoral lymphocytic infiltration might support non-NE features in breast carcinomas.

Metastatic breast cancer simulating well-differentiated neuroendocrine neoplasms of visceral organs

A series of metastatic breast carcinoma (MBC) mimicking visceral well-differentiated neuroendocrine neoplasms has not previously been reported. We identified 5 consultation cases originally submitted as neuroendocrine neoplasms in women but that were found to be MBC on subsequent review. All 5 neoplasms demonstrated nested architecture and relatively uniform nuclei. Four patients had a known history of breast cancer (remote in 3 and concurrent in 1), but the metastases (3 liver, 1 lung) labeled for chromogranin and/or synaptophysin, prompting misdiagnosis as neuroendocrine neoplasm. In a fifth case, a liver metastasis in a patient with a known pancreatic endocrine neoplasm was originally thought to be of pancreatic origin; an occult concurrent primary breast cancer (PBC) was subsequently identified as the source. On further immunohistochemistry (IHC), all metastases evaluated were diffusely, strongly positive for estrogen receptor (5/5 cases) and GATA3 (4/4 cases). Three patients had previously received ineffective treatment for neuroendocrine carcinoma. Based on the consultation diagnosis, all 4 patients with follow-up received hormone therapy, which was effective in 3. In a separate tissue microarray cohort of paired PBCs and hematogenous MBCs, chromogranin and/or synaptophysin IHC labeling was typically negative and increased from the PBC to the MBC in only 5% of cases. In conclusion, although neuroendocrine differentiation is uncommon in breast cancer and does not commonly increase in metastases, MBC with neuroendocrine differentiation should be considered in patients with visceral neuroendocrine neoplasms of unknown primary site. Diffuse IHC labeling for estrogen receptor and GATA3 helps establish the correct diagnosis.

Dramatic response to cyclin D-dependent kinase 4/6 inhibitor in refractory poorly differentiated neuroendocrine carcinoma of the breast

Neuroendocrine tumors are a rare subset of breast carcinomas. Commonly, platinum-based doublet is used as a systemic treatment option for high-grade neuroendocrine carcinomas from lung, gastrointestinal, and genitourinary origins. In comparison to other breast cancers, neuroendocrine carcinomas have unique genomic features and different treatment strategies. We present a patient with high-grade neuroendocrine carcinoma of the breast who had a successful and durable response to the cyclin D-dependent kinase (CDK) 4/6 inhibitor palbociclib in conjunction with endocrine therapy. This patient was refractory to commonly used platinum-based chemotherapy as well as hormone-based treatment. To date, this is the first published case of use of CDK 4/6 inhibitor in primary neuroendocrine carcinoma of the breast.

Primary breast carcinomas with neuroendocrine features: Clinicopathological features and analysis of tumor growth patterns in 36 cases

Primary breast carcinoma with neuroendocrine features (NEBC) is an uncommon tumor. In the classification of WHO 2012, these tumors were categorized as: 1- neuroendocrine tumor, well-differentiated; 2- neuroendocrine carcinoma, poorly differentiated/small cell carcinoma; and 3- invasive breast carcinoma with neuroendocrine differentiation. In this study, we reviewed NEBC except poorly differentiated/small cell carcinoma variant in order to define the morphological growth patterns and cytonuclear details of these tumors. All breast surgical excision materials between 2007 and 2016 were re-evaluated in terms of neuroendocrine differentiation. Thirty-six cases showing positive staining for synaptophysin and/or chromogranin A in ≥50% of tumor cells were included in the study. All cases were female with a mean age of 67.4. Mean tumor diameter was 26 mm. Multifocality was noted in 5 cases. Grossly, they were mostly infiltrative mass lesions. T stages, identified in 34 cases, were as follows: 13 cases with pT1; 19 pT2 and 2 pT3. We described schematically 4 types of patterns depending on predominant growth pattern, except one case: 1) Large-sized solid cohesive groups (6 cases), 2) Small- to medium-sized solid cohesive groups with trabeculae/ribbons and glandular structures (6 cases), 3) Mixed growth patterns (20 cases), 4) Invasive tumor with prominent extracellular and/or intracellular mucin (3 cases). The tumor cells were mostly polygonal-oval with eosinophilic/eosinophilic-granular cytoplasm. The nuclei of tumor cells were mostly round to oval with evenly distributed chromatin. Only 5 cases showed high grade nuclear and histological features. Molecular subtypes of the cases were as follows: 33 luminal A, 2 luminal B, and 1 triple negative. NEBC should come to mind when a tumor display one of the morphological patterns described above, composed of monotonous cells with mild to moderate nuclear pleomorphism and abundant eosinophilic/eosinophilic granular or clear cytoplasm, especially in elderly patients.

Primary small cell carcinoma of the breast: a case report

Background

Neuroendocrine breast cancer is a rare entity that was defined in 2003 by the World Health Organization as a separate breast cancer subtype. The diagnosis of neuroendocrine breast cancer requires the presence of neuroendocrine features in at least 50% of malignant cells, the exclusion of non-mammary primary tumors, as well as the presence of an in situ component in breast histology. The treatment and prognosis of neuroendocrine breast cancer are still not well established. Small cell carcinoma of the breast is a subtype of neuroendocrine cancer, resembling small cell carcinoma of the lung. It has a very poor prognosis and warrants treatment with platinum-based chemotherapy.

Case presentation

We herein report the case of a 47-year-old white woman with a left breast mass that was found to be an early-stage, high-grade small cell carcinoma of the breast. Positron emission tomography-computed tomography imaging excluded any other primary disease. Our patient underwent a left total mastectomy with sentinel lymph node biopsy and received cisplatin-based adjuvant chemotherapy. Our patient remains free of disease to date.

Conclusions

This case report sheds light on a rarely described disease and provides a comprehensive approach to diagnosis and management. Neuroendocrine carcinoma of the breast is a well-defined histologic subtype of breast cancer. Small cell carcinoma of the breast is a rare subtype of neuroendocrine breast cancer. Due to the rarity of this entity, prognosis has still not been well established, and treatment has not been standardized, cisplatin-based treatment has been used in this case similar to small cell carcinoma of the lung.

Neuroendocrine Tumors of the Breast

A small but increasingly recognized and studied subset of breast carcinomas are characterized by neuroendocrine (NE) differentiation. As with nearly all forms of breast neoplasia, NE tumors are characterized by considerable heterogeneity in microscopic appearance and clinical aggressiveness. About half of NE breast carcinomas recapitulate the histological spectrum typical of their counterparts in other organ systems, varying from "carcinoid-like" to small cell carcinoma, with most representing intermediate grade tumors. Despite NE morphology, these tumors have a high frequency of estrogen receptor expression. Clinical outcomes of women with NE breast carcinomas are reliably grade and stage dependent. Tumors associated with "solid papillary" differentiation comprise the remaining cases of NE breast neoplasia. Solid papillary carcinoma is an intrinsically low grade/favorable prognosis class of breast neoplasia that usually presents in post-menopausal age groups. About half of solid papillary carcinoma present as a distinctive pattern of ductal carcinoma in situ that may be difficult to recognize owing to its close resemblance to florid proliferative lesions. Invasive solid papillary carcinomas are characterized by a variety of histological patterns and often show mucinous differentiation. Future studies are necessary to better define the histogenesis, optimal classification, and improved directed therapies for NE breast neoplasia.

Neuroendocrine Carcinoma of the Breast: Current Evidence and Future Perspectives

: Neuroendocrine carcinoma of the breast is considered a rare entity, and for this reason there are no data from prospective clinical trials on its optimal management. Early stage tumors are usually treated with the same strategy used for the other types of invasive breast cancer. Anthracycline- and taxane-based regimens represent the most frequently administered chemotherapy in neoadjuvant and adjuvant setting, as well as for metastatic disease, although combinations of platinum compounds and etoposide have been widely used, in particular for small-cell histology and tumors with a high proliferation index. For metastatic disease, a multimodality therapeutic strategy can be considered on an individual basis, with chemotherapy, endocrine therapy, peptide receptor radionuclide therapy, radiation therapy, surgery, or a combination of the above. In the near future, a better knowledge of the biology of these tumors will hopefully provide new therapeutic targets for personalized treatment. In this review, we discuss the current evidence and the future perspectives on diagnosis and treatment of neuroendocrine carcinoma of the breast.

IMPLICATIONS FOR PRACTICE

Neuroendocrine carcinoma of the breast (NECB) is a distinct entity of breast cancer. Clinical features and morphology are not helpful to distinguish NECB from other subtypes of breast cancer; therefore, immunohistochemistry markers for neuroendocrine differentiation, mainly chromogranin and synaptophysin, should be routinely used to confirm the diagnosis, especially in cases of mucinous or solid papillary carcinoma in which the suspicion of NECB may be relevant. Adjuvant treatment should be offered according to the same recommendations given for the other types of invasive breast cancer. An accurate diagnosis of NECB is also important in the metastatic setting, in which a multimodality approach including specific therapies such as peptide receptor radionuclide therapy can be considered.

Cytokeratin 7 negative invasive breast carcinoma: clinicopathological and immunohistochemical analysis of 14 cases with clinical follow-up

Cytokeratin 7 (CK 7) negative breast tumours are reported to occur rarely. We studied 14 CK 7 negative cases of primary invasive ductal carcinoma (IDC) detected during sentinel lymph node metastases work-up and immunohistochemistry panel in the work-up of metastatic carcinoma of unknown origin. Axillary lymph node metastases were present in seven patients (50%). Oestrogen receptor (ER) was strongly positive in all cases: progesterone receptor in 78%, Her-2/neu in 7% and high proliferation index with Ki-67 >20% was seen in 71% of the cases. Metastatic and/or recurrence were found in 8 of 14 patients (57%) with the mean clinical follow-up of 55 months. Metastatic sites include multiple bones, brain, spinal cord, liver, pancreas, ovary, lung, lymph node other than ipsilateral axillary and skin. 12 of 14 patients received adjuvant chemotherapy. All 14 patients received hormonal therapy and radiation therapy. Morphologically, IDC with neuroendocrine features was noted in 57%. Synaptophysin stain was positive in 57% and chromogranin was positive in 21% of the cases. In conclusion, these CK 7 negative breast carcinomas were ER positive, mostly Her-2/neu negative, had high Ki-67 and frequently showed neuroendocrine differentiation. More than half of these cases had a poor outcome.

Fine-needle aspiration detects primary neuroendocrine carcinoma of the breast in a patient with breast implants

Breast augmentation with implantation represents a challenge for subsequent radiographic imaging and pathological sampling. Fine-needle aspiration biopsy (FNAB) is an excellent technique to sample suspicious lesions that are adjacent to fragile implants. We report a case of a 51-year-old woman with breast implants presenting with an initial diagnosis of fibroadenoma by imaging studies. A definite diagnosis of mammary carcinoma with plasmacytoid cells was made on ultrasound (US)-guided FNAB of the breast mass with rapid on-site evaluation which initiated core needle biopsy of the mass and subsequent mastectomy with sentinel lymph node biopsy. Our case exemplifies the role of US-guided FNAB for the initial investigation of breast masses in patients with implants. In addition, the case illustrates the cytomorphological features of the tumor cells in primary neuroendocrine carcinoma of the breast.

Papillary and neuroendocrine breast lesions: the WHO stance

In this review, we highlight adaptations in the WHO 2012 classification of papillary and neuroendocrine breast lesions as compared with the previous 2003 version. Consensus criteria for distinguishing atypical ductal hyperplasia from ductal carcinoma in situ within an intraductal papilloma are proposed. The absence of myoepithelial cells around the wall of an encapsulated papillary carcinoma, although raising consideration of an indolent tumour with minimal invasion, is currently regarded as in-situ disease for staging purposes. The majority of solid papillary carcinomas are classified as in-situ tumours, but lesions with irregular tumour islands within desmoplastic stroma may be considered to be invasive. The diagnosis of solid papillary carcinoma without further qualification as either in-situ or invasive disease is discouraged. When invasive papillary carcinoma is seen in the breast, metastatic papillary carcinoma from other organ sites needs to be excluded. WHO 2012 classifies neuroendocrine breast tumours as well-differentiated neuroendocrine tumour, small-cell carcinoma, and invasive breast carcinoma with neuroendocrine differentiation. There is currently no clinical impact of identifying neuroendocrine differentiation in conventional invasive breast carcinomas, apart from acknowledging its frequent occurrence in subtypes such as the hypercellular variant of mucinous carcinoma and solid papillary carcinoma.

Primary neuroendocrine carcinoma of the breast: clinical, imaging, and histologic features

OBJECTIVE

The purpose of this study was to evaluate the clinical, imaging, and histopathologic findings of primary neuroendocrine carcinoma of the breast.

MATERIALS AND METHODS

A pathology database was searched for the records of patients with a histopathologic diagnosis of primary neuroendocrine carcinoma of the breast who had undergone mammography, sonography, or MRI between 1984 and 2011. The imaging studies of eligible patients were retrospectively reviewed according to the BI-RADS lexicon, and clinical presentation and histopathologic characteristics were documented. Imaging characteristics were compared with historical controls of invasive mammary carcinoma.

RESULTS

Eighty-seven patients (84 women, three men; mean age, 62.9 years; range, 28-89 years) were included in the study. The mean tumor size was 3.1 cm (range, 0.6-11 cm). Sixty-five of 84 (77.4%) cancers were estrogen and progesterone receptor positive and ERBB2 negative. A palpable mass (55.8%) was a common clinical manifestation. A high-density, round or oval, or lobular mass with nonspiculated margins on mammograms and an irregular (65.4%), hypoechoic (78.4%) mass, with indistinct margins (43.5%), no or enhanced posterior acoustic features (77.9%) on sonograms were common findings. MRI revealed an irregular mass (83.3%), irregular margins (63.6%), and washout kinetics (85.7%). Neuroendocrine carcinoma presented more frequently as masses on mammograms. Calcifications were infrequent compared with their occurrence in invasive mammary cancer.

CONCLUSION

Primary neuroendocrine carcinoma of the breast has mammographic features that differ from those of invasive mammary carcinoma. A round, oval, or lobular mass with nonspiculated margins, positive estrogen and progesterone receptor results, and negative ERBB2 results should raise suspicion of primary neuroendocrine carcinoma.

Primary small-cell neuroendocrine carcinoma of the male breast: a rare case report with review of the literature

In this case study and review, we present a case of a primary small-cell neuroendocrine carcinoma (SCNC) of the male breast. Primary SCNC of the breast is a rare tumor with less than 30 cases reported in the literature. Most cases are found in women. Another exceptional point is that human epidermal growth factor receptor-2 (Her-2) immunoreactivity was positive in our recent case, which differed to previous reports detailing SCNC in women. We have no evidence to demonstrate the differences between treatment and prognoses for males and females, because we do not have sufficient cases to undertake an evidence-based investigation. We provide this rare case history; review the literature on SCNC of the breast; and discuss detailed information regarding epidemiology, histogenesis, clinical and histologic diagnosis criteria, surgical and adjuvant treatment, and prognosis.

Peptide Receptor Radionuclide Therapy (PRRT) in a Patient Affected by Metastatic Breast Cancer with Neuroendocrine Differentiation

BACKGROUND

Breast cancer (BC) is the most frequent cancer in European women with nearly 30% of the patients eventually developing metastases. Neuroendocrine differentiation is a rare event, but overexpression of somatostatin receptors in BC has been reported in many studies.

CASE REPORT

A patient with liver metastases from BC was treated with peptide receptor radionuclide therapy (PRRT). Computed tomography scan and biochemical examinations showed a clear response to radionuclide therapy.

CONCLUSION

PRRT may be useful in metastatic BC patients.

Locally-advanced primary neuroendocrine carcinoma of the breast: case report and review of the literature

Background

Primary neuroendocrine carcinoma of the breast is a heterogeneous group of rare tumors with positive immunoreactivity to neuroendocrine markers in at least 50% of cells. Diagnosis also requires that other primary sites be ruled out and that the same tumor show histological evidence of a breast in situ component. Primary neuroendocrine carcinoma of the breast rarely presents as locally advanced disease and less frequently with such widespread metastatic disease as described herein. The review accompanying this case report is the first to provide an overview of all the cases of primary neuroendocrine carcinoma of the breast published in the literature and encompasses detailed information regarding epidemiology, histogenesis, clinical and histologic diagnosis criteria, classification, surgical and adjuvant treatment, as well as prognosis. We also provide recommendations for common clinical and histologic pitfalls associated with this tumor.

Case presentation

We describe a case of a 51-year-old Hispanic woman initially diagnosed with locally-advanced invasive ductal carcinoma that did not respond to neodjuvant treatment. After undergoing modified radical mastectomy the final surgical pathology showed evidence of alveolar-type primary neuroendocrine carcinoma of the breast. The patient was treated with cisplatin/etoposide followed by paclitaxel/carboplatinum. Thirteen months after surgery the patient is alive, but developed pulmonary, bone, and hepatic metastasis.

Conclusion

The breast in situ component of primary neuroendocrine carcinoma of the breast may prevail on a core biopsy samples increasing the probability of underdiagnosing this tumor preoperatively. Being aware of the existence of this disease allows for timely diagnosis and management. Optimal treatment requires simultaneous consideration of both the neuroendocrine and breast in situ tumor features.

Neuroendocrine tumor, well differentiated, of the breast: a relatively high-grade case in the histological subtype

Primary neuroendocrine carcinoma of the breast is a rare entity, comprising <1% of breast carcinomas. Described here is the case of a 78-year-old woman who developed an invasive tumor in the left breast measuring 2.0 cm x 1.5 cm x 1.2 cm. The tumor was composed of only endocrine elements in the invasive part. It infiltrated in a nested fashion with no tubular formation. Intraductal components were present both inside and outside of the invasive portion. Almost all carcinoma cells consisting of invasive and intraductal parts were positive for synaptophysin and neuron-specific enolase. According to the World Health Organization classification 2012, this tumor was subclassified as neuroendocrine tumor, well-differentiated. Among the subgroup, this tumor was relatively high-grade because it was grade 3 tumor with a few mitotic figures. Vascular and lymphatic permeation and lymph node metastases were noted. In the lymph nodes, the morphology of the tumor was similar to the primary site. No distant metastasis and no relapse was seen for one year after surgery. The prognosis of neuroendocrine carcinomas is thought to be worse than invasive mammary carcinomas, not otherwise specified. Therefore, immunohistochemistry for neuroendocrine markers is important in the routine practice to prevent overlooking neuroendocrine carcinomas.

Does hormonal therapy have a therapeutic role in metastatic primary small cell neuroendocrine breast carcinoma? Case report and literature review

Primary neuroendocrine carcinoma of breast (NECB) is a very rare tumor; the World Health Organization(WHO) subcategorized these tumors into 3 major histologic subtypes: solid, small cell carcinoma (SMCC), and large cell NE carcinoma. The SMCC subtype is the least common and most aggressive and has been reported to be as aggressive as its pulmonary counterpart. SMCC is usually confirmed based on clinical, pathologic,and imaging studies. Local disease is usually managed in a fashion similar to that of the usual ductal breast cancer; in the metastatic SMCC setting, regimens that are implemented in small cell lung cancer are usually attempted, according to case reports and published small case series. Hormone receptors can be expressed in more than 90% of the solid tumor subtype; however its expression is manifested in about 50% of cases of SMCC. Although hormonal therapy can be used successfully to treat the usual metastatic ductal breast cancer,its utility in metastatic SMCC has not been reported. We report an impressive response to hormonal therapy in a patient with late relapse of breast carcinoma with a metastatic SMCC subtype that expressed hormone receptors. The response to hormonal therapy was sustained for about 12 months. The response to hormonal therapy is definitely an interesting finding that, to our knowledge, has not been described before in the setting of metastatic SMCC. We suggest considering adding hormonal therapy to the treatment pipeline for primary SMCC of the breast that express hormone receptors.