Fibroepithelial tumors of the breast: pathologic and immunohistochemical features and molecular mechanisms

Giant Borderline Phyllodes Tumor of the Breast: A Case Report

Borderline phyllodes tumor is a rare and benign form of breast cancer with malignant potential. According to the World Health Organization (WHO), phyllodes tumor is classified into three categories: benign, borderline, and malignant. The treatment of phyllodes tumor is wide focal excision combined with radiotherapy and chemotherapy in certain cases. Herein, we report a 47-year-old female who presented with a giant borderline mass approximately 19.5 x 16.9 x 9.3 cm in size. From medical history, we noticed that the mass begun to develop during puberty. Wide focal excision of the tumor and immediate implant-based reconstruction with free nipple graft was performed, with the tumor specimen measuring 16.5 x 14.2 x 8.7 cm. Histological examination reported a borderline phyllodes tumor, and in this case, the patient did not undergo adjuvant treatment.

Stromal Ki67 Expression Might be a Useful Marker for Distinguishing Fibroadenoma From Benign Phyllodes Tumor of the Breast

Background. Fibroadenoma (FA) and benign phyllodes tumor (PT) of the breast often have similar appearances on imaging. While an exact diagnosis of biopsy specimens is required to choose adequate treatment, including surgical procedures, it is sometimes difficult to pathologically differentiate these 2 tumors due to histological resemblances. To elucidate markers for distinguishing FA from benign PT, we analyzed clinical samples immunohistochemically. Methods. We retrospectively investigated 80 breast fibroepithelial lesions. As a discovery set, 60 surgical excision samples (30 FA and 30 benign PT) were examined. Twenty biopsy samples (10 FA and 10 benign PT) were examined as a validation set. To determine targets for immunohistochemistry, we first tested some proteins based on previous reports. As a result, Ki67 was chosen for differentiating FA and PT; thus further examinations were conducted with this protein. Results. Among the proteins examined, stromal Ki67 was significantly higher in PT than in FA. Benign PT had significantly higher stromal Ki67 expression both at random and at hotspots (p < .001 and <.001, respectively). The receiver operating characteristic curve analysis identified 3.5% and 8.5% (at random spots and hotspots, respectively) as the optimal cutoff values of stromal Ki67 for distinguishing between these 2 tumors. In the validation cohort employing needle biopsy specimens, we confirmed that these 2 cutoff values properly classified these 2 tumors (p = .043 and .029, respectively). Conclusion.We revealed that stromal Ki67 might be a potential marker for distinguishing FA from benign PT.

Epithelial to mesenchymal transition (EMT) in metaplastic breast cancer and phyllodes breast tumors

Epithelial-mesenchymal transition (EMT), a transdifferentiation program whereby epithelial cells acquire mesenchymal phenotype, is essential during embryonic development. EMT has also been implicated in cancer progression by conferring migratory and metastatic potential, as well as cell plasticity and stem cell like traits, to cancer cells. Metaplastic breast carcinoma (MBC) is a rare aggressive type of breast cancer characterized by the presence of heterologous elements, typically by the existence of epithelial and mesenchymal components. Phyllodes tumors (PTs) are uncommon fibroepithelial neoplasms consisting of epithelial and mesenchymal elements. Although various hypotheses have been proposed on the pathogenesis of these biphasic tumors, there is growing evidence supporting the theory that PTs and MBC could both correlate with cancer related EMT. This review summarizes the existing literature on the emerging role of EMT in the pathogenesis of MBC and PTs. Both malignant PTs and MBC are characterized by poor prognosis. Therefore, several anti-EMT targeting strategies such as blocking upstream signaling pathways, targeting the molecular drivers of EMT and targeting mesenchymal cells and the extracellular matrix, could potentially represent a promising therapeutic approach for patients suffering from these aggressive neoplasms.

The Genetic Landscape of Fibroepithelial Lesions of the Breast

Fibroepithelial lesions of the breast encompass a broad spectrum of lesions from fibroadenomas and their variants to phyllodes tumors, including their clinical range of benign, borderline, and malignant. Classification of this spectrum of neoplasms has historically and currently been based purely on morphology, although the nomenclature has shifted over the years largely due to the significant histologic overlap that exists primarily within the cellular fibroadenomas to borderline malignant phyllodes tumor categories. A review of the current diagnostic challenge, proposed ancillary studied and their value in prognostic significance, is provided. This article highlights the most recent molecular and genetic findings as well as the limitations of the studies, in the context of practical and available applications for the diagnostician and managerial implications for the clinician.

Bilateral Concurrent Benign Phyllodes Tumor in a 43-Year-Old Female: A Case Report

Phyllodes tumor is considered a rare form of breast tissue neoplasm that presents as a rapidly growing painless mass. This neoplasm is classified as benign, borderline, or malignant and standard treatment consists of surgical excision with clear margins. The vast majority of reported cases have described the unilateral presentation of this tumor, making bilateral presentation a rare find. Our case describes a 43-year-old Hispanic woman with a history of fibroadenomas who was found to have concurrent benign bilateral phyllodes tumors.

An integrative approach for exploring the nature of fibroepithelial neoplasms

BACKGROUND

Malignant phyllodes tumour (MPT) is a rare breast malignancy with epithelial and mesenchymal features. Currently, there are no appropriate research models or effective targeted therapeutic approaches for MPT.

METHODS

We collected fresh frozen tissues from nine patients with MPT and performed whole-exome and RNA sequencing. Additionally, we established patient-derived xenograft (PDX) models from patients with MPT and tested the efficacy of targeting dysregulated pathways in MPT using the PDX model from one MPT.

RESULTS

MPT has unique molecular characteristics when compared to breast cancers of epithelial origin and can be classified into two groups. The PDX model derived from one patient with MPT showed that the mouse epithelial component increased during tumour growth. Moreover, targeted inhibition of platelet-derived growth factor receptor (PDGFR) and phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) by imatinib mesylate and PKI-587 showed in vivo tumour suppression effects.

CONCLUSIONS

This study revealed the molecular profiles of MPT that can lead to molecular classification and potential targeted therapy, and suggested that the MPT PDX model can be a useful tool for studying the pathogenesis of fibroepithelial neoplasms and for preclinical drug screening to find new therapeutic strategies for MPT.

Gene expressions and their significance in organoid cultures obtained from breast cancer patient-derived biopsies

Gene expression changes are one of the hallmarks of malignant cells and such changes in specific genes have been identified for a variety of human cancers. Such an association in gene expression changes becomes very significant for breast cancers due to the genetic heterogeneity seen in such cancers. It is due to such genetic implication that breast cancers are classified into several subtypes; based on the expression and the magnitude of expression of estrogen and progesterone receptor genes. Changes in the expression of ERBB2, ESR1, PLAU, MUC1, PGR, and TP53 are implicated in breast cancers. Of the various models available for cancer research, organoid cultures from patient-derived biopsies are being considered as the most relevant for invitro testing. Organoid cultures derived from patient biopsies mitigate several limitations of other commonly available models such as cancer cell lines. Such organoids retain the functional physiology of solid tumors which include gene expression. Also, utilizing patient derived organoids for in vitro testing paves way for personalized medicine which greatly enhances the effectiveness of cancer therapy for individuals. We present the genes implicated in breast cancers, the ways in which organoids can be derived from breast cancer biopsies and their applications for gene expression studies.

Fibroepithelial Breast Tumors in a Teenager with Beckwith-Wiedemann Syndrome: A Case Report and Review of Literature

Beckwith-Wiedemann syndrome (BWS) is a human genomic imprinting disorder that presents with a wide spectrum of clinical features, including overgrowth, abdominal wall defects, macroglossia, neonatal hypoglycemia, and predisposition to embryonal tumors. Its diagnosis is based on molecular tests or clinical signs. However, in children with features of BWS who do not fulfill the clinical diagnostic criteria, the molecular tests may play an important role in the diagnosis. There is an increased risk of embryonal tumors in patients with BWS, but few case reports have been reported on benign breast tumors in female adolescents with this syndrome. To our knowledge, this is the first case report in the literature that describes the imaging findings of fibroepithelial breast tumors (phyllodes tumor and fibroadenomas) in a 13-year-old female with BWS, highlighting the need for lifelong tumor surveillance in this patient population.

Recurrent phyllodes tumour of breast infiltrating the latissimus dorsi reconstruction flap

Phyllodes tumour is a rare breast tumour with potential of malignancy. Recurrence in phyllodes tumour may also be suggestive of malignant transformation. We report a case of 29-year-old woman with recurrent phyllodes tumour infiltrating the latissimus dorsi reconstruction flap. Re-excision of the tumour along with excision of latissimus dorsi flap was done. Histopathology confirmed malignant phyllode tumour. A significantly higher incidence of recurrence is seen in phyllodes tumour of large size, tumours with infiltrative borders, increased mitotic activity, malignant histology and positive margins. Surgeons should always take into consideration the risk factors for recurrence before planning reconstructive breast surgery in recurrent phyllodes tumour. A preoperative MRI imaging and incisional biopsy are essential in planning surgery for these patients.

Breast fibroadenomas: a review in the light of current literature

&lt;br&gt;&lt;b&gt;Introduction:&lt;/b&gt; Fibroadenomas are one of the most common benign tumors of the breast in the adolescent females accounting for about 2/3&lt;sup&gt;rd&lt;/sup&gt; of all the breast lumps and more than half of all the biopsied breast lesions. They come into being due to overgrowth of glandular tissue under the influence of hormonal changes that the girls undergo at the time of puberty. Due to the wide prevalence of fibroadenomas and the psychosocial morbidity associated with the finding of a breast mass, it is imperative for physicians treating adolescent patients to be thoroughly familiar and updated with this disease. &lt;br&gt;&lt;b&gt;Aim:&lt;/b&gt; The article aims at providing a brief review of the classification, presentation, diagnosis, and update on the management of breast fibroadenomas on the basis of recent literature.

Droplet-digital PCR reveals frequent mutations in TERT promoter region in breast fibroadenomas and phyllodes tumours, irrespective of the presence of MED12 mutations

BACKGROUND

Breast fibroadenoma (FA) and phyllodes tumour (PT) often have variations of gene mediator complex subunit 12 (MED12) and mutations in the telomerase reverse transcriptase promoter region (TERTp). TERTp mutation is usually tested by Sanger sequencing. In this study, we compared Sanger sequencing and droplet-digital PCR (ddPCR) to measure TERTp mutations in FA and PT samples.

METHODS

FA and PT samples were collected from 82 patients who underwent surgery at our institution from 2005 to 2016. MED12 mutations for all cases and TERTp mutations for 17 tumours were detected by Sanger sequencing. ddPCR was performed to analyse TERTp mutation in all cases.

RESULTS

A total of 75 samples were eligible for analysis. Sanger sequencing detected MED12 mutations in 19/44 FA (42%) and 21/31 PT (68%). Among 17 Sanger sequencing-tested samples, 2/17 (12%) were TERTp mutation-positive. In ddPCR analyses, a significantly greater percentage of PT (19/31, 61%) was TERTp mutation-positive than was FA (13/44, 30%; P = 0.0046). The mutation positivity of TERTp and MED12 did not correlate, in either FA or PT.

CONCLUSIONS

ddPCR was more sensitive for detecting TERTp mutation than Sanger sequencing, being able to elucidate tumorigenesis in FA and PT.

Phyllodes Tumors of the Breast: A Literature Review

Phyllodes tumors (PTs) of the breast are considered a rare fibroepithelial neoplasms of the breast and are considered a challenging for both pathologists and surgeons. The World Health Organization (WHO) has classified PTs histologically as benign, borderline, and malignant. PTs can be detected in all ages; however, the median age of presentation is 45 years. PTs can mimic fibroadenoma in clinical presentations. Breast imaging is also similar to fibroadenomas. Cytological diagnosis of PTs by biopsy is usually unreliable. However, a core needle biopsy is superior to fine-needle aspiration. Surgery is considered the mainstay treatment for PTs of the breast with a goal of achieving negative margins. Adjuvant chemotherapy and radiation therapy use for malignant PTs are controversial.

Core needle biopsy diagnosis of fibroepithelial lesions of the breast: a diagnostic challenge

Fibroepithelial lesions (FEL) of the breast are biphasic neoplasms consisting of proliferative epithelial and stromal components and include fibroadenoma, phyllodes tumour and periductal stromal tumour. Core needle biopsy (CNB) is a commonly used diagnostic modality for investigation of breast lesions. As the accurate diagnosis of FEL requires integrated assessment of both epithelial and stromal components, this may create problems in small biopsies with limited sampling. In this review, common problems encountered in CNB of FEL are discussed, including establishing a diagnosis of borderline/malignant phyllodes tumour in a biopsy consisting of malignant spindle cells, differentiating phyllodes tumour from fibroadenoma on CNB, grading of phyllodes tumour of intermediate histological grade and assessment of periductal stromal tumours. The approaches are detailed systematically based on histology, immunohistochemistry and molecular characterisation. This comprehensive approach may aid in dealing with the overlapping histological appearance of FEL and sampling limitations of CNB.

Periductal Stromal Tumors and Phyllodes Tumors Represent a Spectrum of Fibroepithelial Lesions: What Is in a Name?

Periductal stromal tumors (PSTs) of the breast are considered as a rare subtype of phyllodes tumors. These rare fibroepithelial lesions display a biphasic morphology, characterized by a cellular stroma surrounding benign ducts. Unlike phyllodes tumors, they do not present with a leaflike architecture, rendering a biopsy diagnosis of a PST very challenging. In this report, we compare the histopathological features of a PST with those of a borderline phyllodes tumor. We discuss the differences and similarities between both entities, and we highlight the potential pitfalls of the respective biopsies. Both cases illustrate that PSTs and phyllodes tumors are part of the same spectrum. This biological spectrum implies that "hybrid" lesions do exist, which can be hard to classify.

Preoperative prediction of margin requirement following a core biopsy result suggestive of a phyllodes tumour

AIM

To determine if imaging features of lesions with a core biopsy suggestive of a phyllodes tumour can be used to identify which lesions require surgical excision with margins.

MATERIALS AND METHODS

Thirty-one lesions were identified from a prospective database of ultrasound visible masses. Demographic, mammographic, and ultrasound features were assessed while blinded to surgical outcome. Features of those lesions requiring a margin and those that did not were compared. Statistical significance was established using the chi-square test and receiver operating characteristic (ROC) curves.

RESULTS

Thirteen lesions (42%) required a margin and 18 lesions (58%) did not. Features found significantly more frequently in those requiring a margin were a poorly defined margin on mammography (7/9 [78%] versus 4/13 [31%]; p=0.04) and at ultrasound, an irregular margin (8/13 [62%] versus 3/18 [17%]; p=0.01), micro-lobulations (7/13 [54%] versus 3/18 [17%]; p=0.028), mixed echogenicity (9/13 [69%] versus 1/18 [6%]; p=0.0002), echogenic clefts (6/13 [46%] versus 1/18 [6%]; p=0.007), posterior enhancement (9/11 [82%] versus 6/18 [33%]; p=0.01), large size (p=0.003) and stiffness at shear-wave elastography (p=0.026). All six screen-detected lesions were benign.

CONCLUSIONS

There are multiple preoperative features that can be used to guide surgical management of lesions with a preoperative core biopsy result suggestive of a phyllodes tumour.

Core needle biopsy of benign, borderline and in-situ problematic lesions of the breast: Diagnosis, differential diagnosis and immunohistochemistry

Core needle biopsy (CNB) is the most common sampling technique for the histologic evaluation of breast abnormalities. Diagnosing benign proliferative, borderline and some in-situ lesions in CNB is challenging and subject to a significant degree of interobserver variability. In addition, due to the inherent limitations of CNB, "upgrading" to a more significant pathology at excision is an important consideration for some lesions. Pathologists carry a major responsibility in patient diagnosis, risk stratification and management. Familiarity with the histologic features and the clinical significance of these common and problematic lesions encountered in CNB is necessary for adequate treatment and patient follow-up. This review will focus on benign, atypical and in-situ epithelial proliferations, papillary lesions, radial sclerosing lesions, adenosis and cellular fibroepithelial lesions. Highlights of histologic features, useful strategies for accurate diagnosis, basic immunohistochemistry and management will be presented.

Small G protein signalling modulator 2 (SGSM2) is involved in oestrogen receptor-positive breast cancer metastasis through enhancement of migratory cell adhesion via interaction with E-cadherin

The function of small G protein signalling modulators (SGSM1/2/3) in cancer remains unknown. Our findings demonstrated that SGSM2 is a plasma membrane protein that strongly interacted with E-cadherin/β-catenin. SGSM2 downregulation enhanced the phosphorylation of focal adhesion kinase (FAK; Y576/577), decreased the expression of epithelial markers such as E-cadherin, β-catenin, and Paxillin, and increased the expression of Snail and Twist-1, which reduced cell adhesion and promoted cancer cell migration. Oestrogen and fibronectin treatment was found to promote the colocalization of SGSM2 at the leading edge with phospho-FAK (Y397). The BioGRID database showed that SGSM2 potentially interacts with cytoskeleton remodelling and cell-cell junction proteins. These evidences suggest that SGSM2 plays a role in modulating cell adhesion and cytoskeleton dynamics during cancer migration.

Neoplasm of uncertain behaviour of the breast-a retrospective study in a breast unit

Introduction

Breast lesions include a heterogeneous group of entities with variable clinical behaviour and morphological presentation, mostly classified as benign or malignant, with predictable behaviour. However, there are lesions with clinical, breast imaging and/or biopsy characteristics that do not clarify their nature. These lesions have an uncertain behaviour regarding their malignant potential at diagnosis.We intend to relate the preoperative diagnosis of neoplasm of uncertain behaviour of the breast (NUnBB) regarding the core needle biopsy and the histological result after excisional biopsy.

Methods

This is a retrospective study of patients submitted to local excision of breast lesions with a perioperative diagnosis of NUnBB, classified as 2383 at 'International Statistical Classification of Diseases and Related Health Problems' (ICD 9), between January 2007 and October 2016 in a breast unit.

Results

Ninety-two cases with the diagnosis of NUnBB were analysed: 91 females with a mean age of 59 ± 14 years. All were submitted to local excision of breast lesion as ambulatory surgery with the following histology: 64% benign, 3% malignant potential and 33% malignant. Of those who presented malignant results, 69% underwent a surgical re-intervention for local control of the disease.

Discussion

Regarding the considerable number of malignant lesions at final histology and the high percentage of which are re-operated, NUnBB should be treated with the same priority as a confirmed malignant neoplasm and whenever possible, using the most appropriate surgical technique.

Malignant transformation of phyllodes tumor: a case report and review of literature

Malignant phyllodes may transform from benign phyllodes; low-aggressive malignant phyllodes tumor is manageable by locally wide excision.

Phyllodes tumors of the breast: clinicopathological analysis of 106 cases from a single institution

BACKGROUND

Phyllodes tumors (PT) are uncommon biphasic tumors, accounting for less than 1% of all breast primary neoplasms. They form a wide variety of tumors ranging from benign to malignant. Several histological features are used to grade PT into 3 categories: benign (grade I), borderline (grade II) and malignant (grade III) tumors. The aim of our study was to analyse histolopathological, radiological and clinical features of PT from an experience of a single center.

METHODS

It was a retrospective study including 106 patients diagnosed with phyllodes tumors on surgical specimens at the department of pathology, of Hassan II university hospital (Fez, Morocco), from 2009 to 2016.

RESULTS

The mean age was 33.81 years (range of 13-66 years), and the mean age increases with the tumor grade (mean ages of 32.32, 32.87 and 33.65 years respectively for grade I, II and III PT) (p = 0.023); 78 patients (73.58%) had benign PT, 20 (18.86%) had borderline PT and 8 (7.54%) patients were diagnosed with malignant PT. Mostly, the tumor size was <5 cm (63.2%), with BI-RADS 3 (51 patients, 48.11%). The tumor size and the radiological suspicion (ACR/BI-RADS) increased with the tumor grade (p < 0.001). Mitosis count, cellular atypia and stromal cellularity increased with the tumor grade (p < 0.001). Also, the presence of necrosis is associated with malignant PT (p < 0.001). Before surgery, patients had undergone core needle biopsies (CNB) for diagnostic purpose, and the overral sensitivity of this diagnostic procedure was 71.83%. The sentivity of the CNB decreased from grade I PT to grade III PT (from 56.81% to 37.5%), however its specificity increased from grade I to grade III PT (from 59.25% to 100%).

CONCLUSION

Phyllodes tumors of the breast are rare neoplasms with a wide range of clinicopathologic presentations. The core needle biopsy has a good diagnostic sensitivity compared to definitive diagnosis on surgical specimens. There was a statistically significant association between the histological grade of PT and tumor size, radiological suspicion, mitotic count, cellular atypia, stromal cellularity, and tumor necrosis.

A Case of Benign Phyllodes Tumor in a Transgender Woman Receiving Cross-Sex Hormones

Phyllodes tumor is a relatively uncommon fibroepithelial neoplasm of the breast characterized by proliferation of both stromal and epithelial elements. Benign phyllodes tumors are distinguished from fibroadenomas by their prominent leaf-like architecture and exaggerated intracanalicular stromal growth pattern. Typically, these lesions affect older natal females; however, we present what we believe is the first reported case of benign phyllodes tumor in a hormonally treated transgender woman.

A Clinicopathological Study of Benign Phyllodes Tumour of Breast with Emphasis on Unusual Features

INTRODUCTION

Benign Phyllodes Tumours (PTs) are rare fibroepithelial neoplasms that resemble fibroadenoma. But unlike fibroadenoma, benign PT can recur and both stromal & epithelial components can progress to malignancy. Contrary to earlier belief that benign PT is a stromal neoplasm and possibly arises from fibroadenoma, more recent molecular studies have suggested that both stroma and epithelium can become neoplastic. Sometimes, benign PT can occur synchronously with fibroadenoma. Here histomorphologic analysis of eleven cases of benign PT are presented including some unusual features.

MATERIALS AND METHODS

Eleven cases of benign PT diagnosed between Dec 2014 and Jan 2016 in the Department of Pathology were studied. The demographic and clinicopathological features were analysed.

RESULTS

The most common age group affected was 20-30 years (range: 13-45). Clinical features included pain, lump and bleeding from nipple. The tumour size varied from 2.5-18 cm in diameter. H&E stained sections showed secondary changes (haemorrhage, myxoid, change, cystic degeneration), epithelial hyperplasia (8), squamous & columnar metaplasia (1), benign tubular adenoma like areas (1), Ductal Carcinoma In Situ (DCIS) (1), Invasive Ductal Carcinoma (IDC) (1), Pseudoangiomatous Stromal Hyperplasia (PASH) (1), histologic infarction (2), tumour necrosis (1) and synchronous fibroadenoma (1). Unusual histologic features included atypical ductal hyperplasia, DCIS, IDC, synchronous fibroadenoma and tubular adenoma like areas arising within benign PT.

CONCLUSION

This study shows a spectrum of hyperplastic, metaplastic, dysplastic, benign, in-situ-malignancy and even invasive ductal malignancy occurring in benign PT. Therefore adequate and extensive sampling is recommended for accurate diagnosis.

First International Consensus Conference on lesions of uncertain malignant potential in the breast (B3 lesions)

The purpose of this study is to obtain a consensus for the therapy of B3 lesions. The first International Consensus Conference on lesions of uncertain malignant potential in the breast (B3 lesions) including atypical ductal hyperplasia (ADH), flat epithelial atypia (FEA), classical lobular neoplasia (LN), papillary lesions (PL), benign phyllodes tumors (PT), and radial scars (RS) took place in January 2016 in Zurich, Switzerland organized by the International Breast Ultrasound School and the Swiss Minimally Invasive Breast Biopsy group-a subgroup of the Swiss Society of Senology. Consensus recommendations for the management and follow-up surveillance of these B3 lesions were developed and areas of research priorities were identified. The consensus recommendation for FEA, LN, PL, and RS diagnosed on core needle biopsy or vacuum-assisted biopsy (VAB) is to therapeutically excise the lesion seen on imaging by VAB and no longer by open surgery, with follow-up surveillance imaging for 5 years. The consensus recommendation for ADH and PT is, with some exceptions, therapeutic first-line open surgical excision. Minimally invasive management of selected B3 lesions with therapeutic VAB is acceptable as an alternative to first-line surgical excision.

Role of CD10 Immunohistochemical Expression in Predicting Aggressive Behavior of Phylloides Tumors

BACKGROUND

Phylloides tumors are rare breast neoplasms with a variable clinical course depending on the tumor category. Along with histologic features, the role of immunohistochemical staining has been studied in predicting their behavior.

OBJECTIVES

Our aim was to evaluate the role of CD 10 immunohistochemical staining in predicting survival, recurrence and metastasis in phylloides tumor. We also evaluated correlations of other clinicopathological features with overall and disease-free survival.

MATERIALS AND METHODS

CD10 expression was studied in 82 phylloides tumors divided into recurrent/metastatic and non-recurrent/non-metastatic cohorts. The Chi-square test was applied to determine the significance of differences in CD10 expression between outcome cohorts. Uni and multivariate survival analyses were also performed using log-rank test and Cox regression hazard models.

RESULTS

All 3 metastatic cases, 5 out of 6 (83.3%) recurrent cases and 37out of 73 (50.7%) non-recurrent and non-metastatic cases expressed significant (2+ or 3+) staining for CD10. This expression significantly varied between outcome cohorts (p<0.03). Tumor category and histological features including mitotic count and necrosis correlated significantly with recurrence and metastasis. A significant decrease in overall and disease free survival was seen with CD10 positivity, malignant category, increased mitoses and necrosis. Neither CD10 expression nor any other clinicopathologic feature proved to be an independent prognostic indicator in multivariate analysis.

CONCLUSIONS

CD10 immunohistochemical staining can be used as a predictive tool for phylloides tumor but this expression should be interpreted in conjunction with tumor category.

Phyllodes tumours of the breast: a consensus review

Phyllodes tumours constitute an uncommon but complex group of mammary fibroepithelial lesions. Accurate and reproducible grading of these tumours has long been challenging, owing to the need to assess multiple stratified histological parameters, which may be weighted differently by individual pathologists. Distinction of benign phyllodes tumours from cellular fibroadenomas is fraught with difficulty, due to overlapping microscopic features. Similarly, separation of the malignant phyllodes tumour from spindle cell metaplastic carcinoma and primary breast sarcoma can be problematic. Phyllodes tumours are treated by surgical excision. However, there is no consensus on the definition of an appropriate surgical margin to ensure completeness of excision and reduction of recurrence risk. Interpretive subjectivity, overlapping histological diagnostic criteria, suboptimal correlation between histological classification and clinical behaviour and the lack of robust molecular predictors of outcome make further investigation of the pathogenesis of these fascinating tumours a matter of active research. This review consolidates the current understanding of their pathobiology and clinical behaviour, and includes proposals for a rational approach to the classification and management of phyllodes tumours.

Treatment of Giant Fibroadenoma in Young Women: Results after Tumor Excision without Reconstructive Surgery

Introduction: Giant fibroadenoma (GFA) of the breast is defined as fibroadenoma larger than 5 cm, usually presenting unilaterally and manifesting as breast asymmetry or deformity of the breast. Material and Methods: A retrospective database search was done of all patients with giant fibroadenoma who underwent surgery for GFA in the breast center of Hanover Medical School between 2007 and 2014; all patients with GFA were followed up. Data were analyzed with regard to tumor and patient characteristics and esthetic outcome. Results: A total of 13 patients with symptomatic GFA underwent surgery between 2007 and 2014. Mean patient age was 21.2 years (range 14-31 years). In 8 of 13 patients the tumor had resulted in breast deformity and/or breast asymmetry. Average size of the mass was 10.2 cm (range 8.5-12 cm) and average weight was 203.6 g (range 151.2-323.5 g). Initial clinical suspicion of GFA was confirmed by ultrasound examination. Preoperative core biopsy revealed fibroadenoma in 8/13 cases, cellular fibroepithelial lesions with a differential diagnosis of benign phyllodes tumor in 3 cases and unspecific histological findings in the remaining 2 cases. Conclusion: Excision was done using an inframammary or periareolar approach without reconstructive plasty. The cosmetic results were good, as were the outcomes on follow-up. We therefore favor this surgical technique to treat giant fibroadenoma of similar size to those described above.

IMP3 Is Strongly Expressed in Malignant Phyllodes Tumors of the Breast

Background. Phyllodes tumors (PTs) of the breast are rare biphasic neoplasms and are classified as benign, borderline, or malignant. Many biological markers have been studied to discriminate between different grades of PTs. IMP3 is a member of the insulin-like growth factor II mRNA binding protein (IMP) family and is expressed in developing tissues during embryogenesis, whereas in adult tissues it is found only at low or undetectable levels. IMP3 is considered a marker of biological aggressiveness in many cancers, including breast and lung. The aim of this study was to evaluate the immunohistochemical expression of IMP3 in a series of PTs and to determine its association with histological grade and clinical outcome. Materials and Methods. We reviewed retrospectively 62 cases of PTs including their recurrences and 20 cases of fibroadenoma. PTs have been classified as benign in 40 cases, borderline in 13 cases, and malignant in 9 cases. Results. There were significant differences in IMP3 expression: in malignant PTs IMP3 expression was higher (56% of cases) than in borderline (15%) and benign cases (5%), ( P = .001). Fibroadenoma showed no expression for IMP3. IMP3 expression was different in cases with recurrence than cases without recurrence. Furthermore, 3 of the recurrences had a higher histological grade with a positive IMP3 expression compared with the primary tumor. Conclusions. This is the first study evaluating the IMP3 immunohistochemical expression in PTs. Its expression correlates with histological grade and could be used in the differential diagnosis of fibroepithelial tumors and in predicting a more aggressive behavior.

Benign mimickers of malignant breast lesions

Breast pathology is filled with pitfalls, including underdiagnosis of bland-appearing lesions, both invasive and non-invasive, misdiagnosis of malignant lesions as belonging to the wrong subgroup, for example, calling LCIS as DCIS or missing the metaplastic component of an invasive lesion, and overdiagnosis of benign lesions as malignancy. While each is a sin of varying severity, the overdiagnosis of benign lesions can be the most scarring, especially in this age where Angelina Jolie׳s prophylactic mastectomy is the headline news and patients are pushing for aggressive preventive treatment. In this review, we will consider some of the more common benign lesions and the malignant counterpart that they mimic, with the goal of identifying characteristic features that will lead to the correct diagnosis. Much of the discussions will center around the assessment of core biopsies, as smaller tissue volume is most often contributory to overcalling benign lesions.

Mutational analysis of MED12 exon 2 in a spectrum of fibroepithelial tumours of the breast: implications for pathogenesis and histogenesis

AIMS

Fibroadenomas (FAs) and phyllodes tumours (PTs) are fibroepithelial tumours. Mutations in MED12 exon 2 have been reported in FAs. This study investigated the MED12 mutations in a spectrum of fibroepithelial tumours.

METHODS AND RESULTS

Using direct sequencing, we analysed MED12 exon 2 mutations on 121 samples, including PTs and FAs and variants. We found MED12 mutations in 71.4% of PTs. No significant difference in the mutation frequency was observed between benign, borderline and malignant PTs, and a general lack of correlation existed between mutations and pathological factors associated with PT grading. The mutation patterns were similar between PTs and FAs, with codon 44 being involved most frequently. MED12 mutations were identified in 47.1, 52.6 and 50.0% of complex FAs, juvenile FAs and tubular adenomas (TAs), respectively, and the frequency and mutation patterns were similar between these FA variants and usual FAs.

CONCLUSIONS

The high frequency and similar patterns of MED12 mutations in FAs and various grades of PTs implies that the MED12 mutation is a common and early pathological event in these fibroepithelial tumours. The similar frequency and patterns of the MED12 mutation between FAs and variants suggests that FA variants are bona fide FAs, with identical pathogenesis involving MED12 mutations.

Mediator kinase module and human tumorigenesis

Mediator is a conserved multi-subunit signal processor through which regulatory informatiosn conveyed by gene-specific transcription factors is transduced to RNA Polymerase II (Pol II). In humans, MED13, MED12, CDK8 and Cyclin C (CycC) comprise a four-subunit "kinase" module that exists in variable association with a 26-subunit Mediator core. Genetic and biochemical studies have established the Mediator kinase module as a major ingress of developmental and oncogenic signaling through Mediator, and much of its function in signal-dependent gene regulation derives from its resident CDK8 kinase activity. For example, CDK8-targeted substrate phosphorylation impacts transcription factor half-life, Pol II activity and chromatin chemistry and functional status. Recent structural and biochemical studies have revealed a precise network of physical and functional subunit interactions required for proper kinase module activity. Accordingly, pathologic change in this activity through altered expression or mutation of constituent kinase module subunits can have profound consequences for altered signaling and tumor formation. Herein, we review the structural organization, biological function and oncogenic potential of the Mediator kinase module. We focus principally on tumor-associated alterations in kinase module subunits for which mechanistic relationships as opposed to strictly correlative associations are established. These considerations point to an emerging picture of the Mediator kinase module as an oncogenic unit, one in which pathogenic activation/deactivation through component change drives tumor formation through perturbation of signal-dependent gene regulation. It follows that therapeutic strategies to combat CDK8-driven tumors will involve targeted modulation of CDK8 activity or pharmacologic manipulation of dysregulated CDK8-dependent signaling pathways.

Frequent MED12 mutations in phyllodes tumours of the breast

BACKGROUND

Phyllodes tumours are rare fibroepithelial tumours of the breast, that include benign, borderline, and malignant lesions. Although the molecular basis of phyllodes tumours largely remains unknown, a recent exome study identified MED12 mutations as a sole recurrent genetic alteration in fibroadenoma, a common benign fibroepithelial tumour that shares some histological features with the phyllodes tumour.

METHODS

Forty-six phyllodes tumours and 58 fibroadenomas of the breast were analysed for MED12 mutations by using Sanger sequencing.

RESULTS

MED12 mutations were identified in 37 out of the 46 phyllodes tumours (80%). The prevalence of MED12 mutations was similar among benign (15/18, 83%), borderline (12/15, 80%), and malignant tumours (10/13, 77%). MED12 mutations were also identified in 36 of the 58 fibroadenomas (62%). The mutations were frequent among intracanalicular-type (24/32, 75%) and complex-type lesions (4/6, 67%), but were significantly less common among the pericanalicular-type lesions (8/20, 40%). A microdissection-based analysis showed that MED12 mutations were confined to the stromal components in both phyllodes tumours and fibroadenomas.

CONCLUSIONS

MED12 mutations were frequent among the phyllodes tumours of the breast, regardless of the tumour grade. Phyllodes tumours and fibroadenomas share, at least in part, a common genetic background.

Application of immunohistochemistry in breast pathology: a review and update

CONTEXT

Immunohistochemistry is a valuable tool in routine breast pathology, used for both diagnostic and prognostic parameters. The diagnostic immunomarkers are the scope of this review. Most breast lesions can be diagnosed on routine hematoxylin-eosin sections; however, in several scenarios, such as morphologically equivocal cases or metastatic tumors of unknown primary, the appropriate application of immunohistochemistry adds true value in reaching an accurate diagnosis.

OBJECTIVE

To evaluate the diagnostic utility of the most commonly studied immunomarkers in the field of breast pathology by review of the literature, using the database of indexed articles in PubMed (US National Library of Medicine, Bethesda, Maryland) from 1976 to 2013.

DATA SOURCES

Literature review, and author's research data and personal practice experience.

CONCLUSIONS

The appropriate use of immunohistochemistry by applying a panel of immunomarkers and using a standardized technical and interpretational method will complement the morphologic assessment and aid in the accurate classification of difficult breast lesions and the identification of metastasis from a breast primary.

Next-Gen Sequencing Exposes Frequent MED12 Mutations and Actionable Therapeutic Targets in Phyllodes Tumors

Phyllodes tumors are rare fibroepithelial tumors with variable clinical behavior accounting for a small subset of all breast neoplasms, yet little is known about the genetic alterations that drive tumor initiation and/or progression. Here, targeted next-generation sequencing (NGS) was used to identify somatic alterations in formalin-fixed paraffin-embedded (FFPE) patient specimens from malignant, borderline, and benign cases. NGS revealed mutations in mediator complex subunit 12 (MED12) affecting the G44 hotspot residue in the majority (67%) of cases spanning all three histologic grades. In addition, loss-of-function mutations in p53 (TP53) as well as deleterious mutations in the tumor suppressors retinoblastoma (RB1) and neurofibromin 1 (NF1) were identified exclusively in malignant tumors. High-level copy-number alterations (CNA) were nearly exclusively confined to malignant tumors, including potentially clinically actionable gene amplifications in IGF1R and EGFR. Taken together, this study defines the genomic landscape underlying phyllodes tumor development, suggests potential molecular correlates to histologic grade, expands the spectrum of human tumors with frequent recurrent MED12 mutations, and identifies IGF1R and EGFR as potential therapeutic targets in malignant cases.

IMPLICATIONS

Integrated genomic sequencing and mutational profiling provides insight into the molecular origin of phyllodes tumors and indicates potential druggable targets in malignant disease. Visual Overview: http://mcr.aacrjournals.org/content/early/2015/04/02/1541-7786.MCR-14-0578/F1.large.jpg.

Interobserver variability by pathologists in the distinction between cellular fibroadenomas and phyllodes tumors

Fibroepithelial lesions with cellular stroma are frequently termed cellular fibroadenomas although criteria for distinguishing them from a phyllodes tumor are vague and subjective. However, the clinical implications and surgical management for these 2 lesions may be different. We randomly selected 21 cases of fibroepithelial lesions sent in consultation to the senior author that were challenging to classify as cellular fibroadenoma or phyllodes tumor. One to 2 representative slides of each case along with patient age were sent to 10 pathologists who specialize in breast pathology. The World Health Organization criteria for phyllodes tumors and a diagnosis form were included with the study set. For the purposes of data reporting, fibroadenoma and cellular fibroadenoma are considered together. In only 2 cases was there uniform agreement as to whether the tumor represented a fibroadenoma or phyllodes tumor. Of the remaining 19 cases, if the diagnoses of fibroadenoma and benign phyllodes tumor were combined and separated from borderline and malignant phyllodes tumors, there was 100% agreement in 53% of cases and 90% agreement in 79% of cases. This study highlights the difficulty that exists in distinguishing some cellular fibroadenomas from phyllodes tumors even for pathologists who specialize in breast pathology. However, there appears to be considerable agreement when cellular fibroadenomas and benign phyllodes tumors are distinguished from borderline and malignant phyllodes tumors. Further studies are needed to determine if there is a clinically significant difference between cellular fibroadenomas and benign phyllodes tumors and how to better distinguish them from borderline and malignant phyllodes tumors.