Predictors of phyllodes tumours on core biopsy specimens of fibroepithelial neoplasms

[Borderlines and malignant phyllodes tumors of the breast: From the anatomopathological challenge to the standard of care]

Phyllodes tumors, borderline (BPT) and malignant (MPT), represent a rare group of fibroepithelial breast tumors. Due to their rarity, their treatment remains poorly codified. The precise incidence of these tumors remains unknown. TPMs represent half of breast sarcomas and 1 % of breast tumors. Their treatment at the localized stage is based on surgery, that can be conservative surgery or a mastectomy. The impact of oncoplastic techniques and immediate breast reconstruction is not documented. The excision margins of the BPT and MPT must be free, a wider margin can provide a benefit in local recurrence but in also overall survival in the case of TPM. The optimal width of the excision margin is not known. In the event of positive margins, a second surgery could make up the result of an insufficient first surgery. Chemotherapy does not seem to provide any benefit on recurrence-free survival, but the available data are particularly weak. The data on adjuvant radiotherapy are more important. This allows better local control in the event of breast-conserving surgery. The benefit of post-mastectomy radiotherapy is less documented but can be considered in cases of poor prognostic factors. The management of TPM at the metastatic stage is based on the use of chemotherapy (anthracyclines, Ifosfamide) and local treatment of metastases in cases of oligometastatic disease. Due to the rarity of these tumors, it is essential that their management be discussed within a network of qualified professionals (NETSARC+).

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.

Multi-recurrent Asynchronous Bilateral Malignant Phyllodes

In this comprehensive study, we present an exceptionally rare case characterized by the occurrence of multi-recurrent asynchronous bilateral malignant phyllodes tumors. Phyllodes tumors, known for their rapid growth, originate within the stromal tissue of the breast and predominantly manifest as benign entities. Our case stands out as an extraordinary anomaly, not only due to its bilateral malignant nature but also owing to the manifestation of a multi-recurrent pattern on both sides. This unprecedented presentation underscores the complexity and heterogeneity of malignant phyllodes tumors, necessitating further in-depth investigation to unravel the underlying mechanisms driving their aggressive behavior and to explore innovative therapeutic strategies aimed at optimizing patient outcomes and prognosis.

Challenges and Clinical Relevance of Modern Breast Pathology Reporting: Your Questions Answered

BACKGROUND

Breast pathology reporting, especially for breast cancer, has evolved through the years, from terse succinct diagnostic conclusions with scant histological details to the current comprehensive reporting guidelines issued by major pathology colleges and bodies, including the International Collaboration on Cancer Reporting. Pathology elements included in reporting guidelines are evidence based and contribute significantly to individualised and personalised patient management.

SUMMARY

This article is based on the lively interactive question and answer session that followed the breast pathology segment in the symposium jointly organised by the British Association of Urological Pathology, British Association of Gynaecological Pathologists, British Society of Gastroenterology and the Association of Breast Pathology, in November 2022, titled "Personalised histopathology reporting for personalised medicine."

KEY MESSAGES

The breast pathology session emphasised the clinical utility of breast pathology data items, incorporating a case-based approach by highlighting the relevance of pathology information in various clinical scenarios. This review included clinico-pathological discussion points on florid lobular carcinoma in situ, atypical apocrine adenosis, post-neoadjuvant chemotherapy reporting, atypical ductal hyperplasia presenting at the margin, flat epithelial atypia versus columnar cell change, papilloma on core needle biopsy, margin status, mucocele-like lesion, total duct excision/microdochectomy specimen, and anterior and nipple margins in skin-sparing mastectomy. Effective communication and regular involvement of pathologists in breast multidisciplinary tumour boards are crucial.

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.

"Growing fibroadenoma": Are there clinical and pathological features predicting a phyllodes tumor on surgical excision?

In cases of growth of FA on imaging, core needle biopsies (CNB) are often performed to rule out phyllodes tumor (PT). We aim to focus on "growing FAs" and to identify clinical and histopathologic features that are likely to predict a PT on excision. Thirty-four FAs with radiologic documentation of growth were included. Various clinical and pathological features such as age, body mass index (BMI), lesion size, and growth rate were recorded. On excision, 17 cases (50 %) were FAs, whereas 16 (47 %) were re-classified as benign PT despite only 19 % being suspicious for PT on CNB. PT patients were older (mean age 42.6) than those with FAs (mean age 28.2), p = 0.0002. All false negative cases demonstrated intracanalicular growth. Mitotic rate was the most significant histologic feature in PT on excision compared to others, such as lesion circumscription and stromal cellularity. Recognition and careful counting of mitotic rate, especially with intracanalicular patterns in growing FAs, can potentially prevent missing a PT on CNB. In patients with "growing FAs" who are ≥40 years of age, excision may be recommended due to the high likelihood of PT diagnosis on excision and high false negative rate on CNB.

Spindle Cell Lesions of the Breast: A Diagnostic Algorithm

CONTEXT.—

Spindle cell lesions of the breast represent a broad spectrum of entities, ranging from nonneoplastic reactive conditions to high-grade malignant tumors. The wide range makes breast spindle cell lesions a diagnostic pitfall.

OBJECTIVE.—

To review the classification of spindle cell lesions of the breast, including clinical features, morphologic characteristics, and the role of immunohistochemistry as well as molecular tools in assisting the differential diagnosis. A diagnostic algorithm will be proposed.

DATA SOURCES.—

Literature and personal experience are the sources for this study.

CONCLUSIONS.—

Spindle cell lesions of the breast can be classified as biphasic or monophasic, with the former including both spindle cell and epithelial components, and the latter including only spindle cell elements. Each category is further subclassified as low or high grade. In the biphasic low-grade group, fibroadenoma and benign phyllodes tumor are the most common lesions. Other uncommon lesions include hamartoma, adenomyoepithelioma, and pseudoangiomatous stromal hyperplasia. In the biphasic high-grade group, borderline/malignant phyllodes tumor and biphasic metaplastic carcinoma are the main lesions to consider. In the monophasic low-grade group, reactive spindle cell nodule, nodular fasciitis, myofibroblastoma, fibromatosis, and fibromatosis-like metaplastic carcinoma have to be considered. In the monophasic high-grade group, the possible lesions are monophasic spindle cell metaplastic carcinoma, primary breast sarcoma, and metastases. Awareness of the clinical history and careful evaluation of any epithelial differentiation (with a large immunohistochemical panel) are crucial in the distinction.

Survey of recurrent diagnostic challenges in breast phyllodes tumours

BACKGROUND

Breast phyllodes tumours (PTs) are graded as benign, borderline, or malignant by analysis of multiple histological features. PT grading is often inconsistent, likely due to variation in the weighting of grading criteria by pathologists.

DESIGN

The hierarchy of use of diagnostic criteria was identified using a 20-question survey.

RESULTS

In all, 213 pathologists from 29 countries responded. 54% reported 10-50 PT cases per year. Criteria considered key to PT diagnosis were: increased stromal cellularity (84.3%), stromal overgrowth (76.6%), increased stromal mitoses (67.8%), stromal atypia (61.5%), stromal fronding (59.0%), periductal stromal condensation (58.0%), irregular tumour borders (46.3%), and/or lesional heterogeneity (33.7%). The importance of grading parameters were: mitotic activity (55.5%), stromal overgrowth (54.0%), stromal atypia (51.9%), increased stromal cellularity (41.7%), and nature of the tumour border (38.9%). 49% would diagnose malignant PT without a full array of adverse features. 89% used the term "cellular fibroepithelial lesion (FEL)" for difficult cases; 45% would diagnose an FEL with stromal fronding (but lacking other PT features) as fibroadenoma (FA), 35% FEL, and 17% PT. 59% deemed clinico-radiological findings diagnostically significant; 68% considered age (≥40 years) important in determining if an FEL was a FA or PT. In FELs from young patients, increased stromal cellularity (83%), fronding (52%), and mitoses (41%) were more common. 34% regarded differentiating cellular FA from PT as a specific challenge; 54% had issues assigning a borderline PT grade.

CONCLUSION

Criteria for grading PT lie on a spectrum, leading to interpretive variability. The survey highlights the criteria most used by pathologists, which do not completely align with WHO recommendations.

Computer-Aided Detection of Quantitative Signatures for Breast Fibroepithelial Tumors Using Label-Free Multi-Photon Imaging

Fibroadenomas (FAs) and phyllodes tumors (PTs) are major benign breast tumors, pathologically classified as fibroepithelial tumors. Although the clinical management of PTs differs from FAs, distinction by core needle biopsy diagnoses is still challenging. Here, a combined technique of label-free imaging with multi-photon microscopy and artificial intelligence was applied to detect quantitative signatures that differentiate fibroepithelial lesions. Multi-photon excited autofluorescence and second harmonic generation (SHG) signals were detected in tissue sections. A pixel-wise semantic segmentation method using a deep learning framework was used to separate epithelial and stromal regions automatically. The epithelial to stromal area ratio and the collagen SHG signal strength were investigated for their ability to distinguish fibroepithelial lesions. An image segmentation analysis with a pixel-wise semantic segmentation framework using a deep convolutional neural network showed the accurate separation of epithelial and stromal regions. A further investigation, to determine if scoring the epithelial to stromal area ratio and the SHG signal strength within the stromal area could be a marker for differentiating fibroepithelial tumors, showed accurate classification. Therefore, molecular and morphological changes, detected through the assistance of computational and label-free multi-photon imaging techniques, enable us to propose quantitative signatures for epithelial and stromal alterations in breast tissues.

Artificial intelligence modelling in differentiating core biopsies of fibroadenoma from phyllodes tumor

Breast fibroepithelial lesions (FEL) are biphasic tumors which consist of benign fibroadenomas (FAs) and the rarer phyllodes tumors (PTs). FAs and PTs have overlapping features, but have different clinical management, which makes correct core biopsy diagnosis important. This study used whole-slide images (WSIs) of 187 FA and 100 PT core biopsies, to investigate the potential role of artificial intelligence (AI) in FEL diagnosis. A total of 9228 FA patches and 6443 PT patches was generated from WSIs of the training subset, with each patch being 224 × 224 pixel in size. Our model employed a two-stage architecture comprising a convolutional neural network (CNN) component for feature extraction from the patches, and a recurrent neural network (RNN) component for whole-slide classification using activation values from the global average pooling layer in the CNN model. It achieved an overall slide-level accuracy of 87.5%, with accuracies of 80% and 95% for FA and PT slides respectively. This affirms the potential role of AI in diagnostic discrimination between FA and PT on core biopsies which may be further refined for use in routine practice.

Which lesions with a radiological or core biopsy diagnosis of fibroadenoma should be excised?

INTRODUCTION

A recent Association of Breast Surgery summary statement on fibroadenoma management recommends excision only for cellular fibroepithelial lesions and rapidly growing lesions with a core biopsy diagnosis of fibroadenoma; persistent pain is a relative indication for excision.

METHODS

This retrospective study looked at the impact this approach would have on the diagnosis of phyllodes tumours.

RESULTS

From 2014 to 2018, there were 1,058 core biopsy diagnoses of fibroadenoma; 112 lesions were excised, of which 98 were fibroadenomas, 4 were hamartomas and 10 were phyllodes tumours. In this group, an excision diagnosis of phyllodes tumour was associated with size more than 40 mm, age more than 40 years and radiological suspicion of phyllodes tumour or carcinoma. One hundred and sixty-six excised fibroepithelial lesions with no previous core biopsy included eight phyllodes tumours; in this group, rapid growth was associated with phyllodes tumour diagnosis. Twelve of the 26 fibroepithelial lesions classified as B3 (cellular fibroepithelial lesion or phyllodes tumour) were diagnosed as phyllodes tumours on excision. Using a combination of radiological, clinical and pathological features it was possible to create an excision policy that would recommend excision of 22 of the 31 phyllodes tumours in this period. Eight of the nine 'missed' phyllodes tumours were benign.

CONCLUSION

The Association of Breast Surgery summary statement will reduce the number of fibroadenomas excised, but may also result in delayed diagnosis of some phyllodes tumours. Appropriate safety netting advice should be provided to identify rapidly growing lesions.

Upstaging of Fibroepithelial Lesions: A Single-Institution Experience

INTRODUCTION

Fibroepithelial lesions of the breast (FEL) are heterogeneous lesions ranging from fibroadenomas (FA) to phyllodes tumors (PT). FEL with cellular stroma are diagnostic challenges on core needle biopsy (CNB) as it is difficult to distinguish cellular FA from PT. The purpose of this study was to determine the features of FEL on CNB that may be predictive of PT, the upstage rate to PT after excision, and the outcomes of those who did not undergo excision.

METHODS

Overall, 305 patients with FEL on CNB between 2009 and 2019 were identified from a prospectively maintained institutional database. Presentation, imaging, and pathology were evaluated.

RESULTS

Mean age at diagnosis was 43.8 years. Pathology on CNB included 97 cases of FEL favoring FA, 19 cases of FEL favoring PT, 3 cases of FEL versus pseudoangiomatous stromal hyperplasia, and 186 cases of FEL not otherwise specified. Following CNB, 96 (31.5%) patients were observed, 158 (51.8%) patients had an excisional biopsy, 48 (15.7%) patients underwent segmental mastectomy, and 3 (1.0%) patients underwent a mastectomy. The upgrade rate from FEL on CNB to PT upon excision was 25.8%. PT on final pathology was more commonly seen when the CNB identified stromal overgrowth, necrosis, and diagnosis of FEL favoring PT. On multivariable analysis, a final diagnosis of PT was associated with age >50 years, larger tumor size >2 cm, stromal overgrowth, and ≥1 mitoses/10 high power fields (HPF) on CNB. Patients who were observed had smaller tumors compared with those who underwent excision.

CONCLUSION

In this 10-year single-institution experience of FEL, the upstage rate to PT was 25.8%. Excision of FEL is recommended. Furthermore, the observation of lesions appeared to be safe in select cases, specifically in patients with smaller tumor size.

Fibroepithelial tumours of the breast-a review

Fibroepithelial tumours of the breast are biphasic neoplasms composed of both epithelial and stromal elements, including the common fibroadenoma and the infrequent phyllodes tumour. The admixture of epithelium and stroma in the fibroadenoma shows intra- and pericanalicular patterns, and may display a variety of histological changes. Fibroadenoma variants include the cellular, juvenile, myxoid and complex forms. The cellular fibroadenoma may be difficult to distinguish from the benign phyllodes tumour. Stromal mitotic activity can be increased in fibroadenomas in the young and pregnant patients. Phyllodes tumours, neoplasms with the potential for recurrence, show an exaggerated intracanalicular growth pattern with broad stromal fronded architecture and stromal hypercellularity. They are graded into benign, borderline and malignant forms based on histological assessment of stromal features of hypercellularity, atypia, mitotic activity, overgrowth and the nature of the tumour borders. Classification of phyllodes tumours is imperfect, compounded by tumour heterogeneity with overlapping microscopic features among the different grades, especially in the borderline category. Malignant phyllodes tumours can metastasise and cause death. Determining which phyllodes tumours may behave aggressively has been difficult. The discovery of MED12 mutations in the pathogenesis of fibroepithelial tumours, together with other gene abnormalities in the progression pathway, has allowed refinements in diagnosis and prognosis.

Updates on Lobular Neoplasms, Papillary, Adenomyoepithelial, and Fibroepithelial Lesions of the Breast

CONTEXT.—

This review article is a result of the breast pathology lectures given at the Sixth Chinese American Pathologists Association annual diagnostic pathology course in October 2020 (held virtually due to the coronavirus disease 2019).

OBJECTIVE.—

To update recent developments, in this review article, the authors wrote minireviews in the following 4 areas: lobular neoplasm, adenomyoepithelial lesions, papillary lesions, and fibroepithelial lesions.

DATA SOURCES.—

The sources include extensive literature review, personal research, and experience.

CONCLUSIONS.—

With the wide practice of screening mammography, these lesions are not uncommon in image-guided core biopsies and excisional specimens. Many recent developments have emerged in understanding these lesions. We aim to provide readers with concise updates for each of these lesions with a focus on recent updates in definitions, diagnostic criteria, management, and molecular profiles that are most relevant to the daily practice of pathology and patient management.

Genetic differences between benign phyllodes tumors and fibroadenomas revealed through targeted next generation sequencing

Breast fibroepithelial lesions are biphasic tumors which comprise the common benign fibroadenomas (FAs) and the rarer phyllodes tumors (PTs). This study analyzed 262 (42%) conventional FAs, 45 (7%) cellular FAs, and 321 (51%) benign PTs contributed by the International Fibroepithelial Consortium, using a previously curated 16 gene panel. Benign PTs were found to possess a higher number of mutations, and higher rates of cancer driver gene alterations than both groups of FAs, in particular MED12, TERT promoter, RARA, FLNA, SETD2, RB1, and EGFR. Cases with MED12 mutations were also more likely to have TERT promoter, RARA, SETD2, and EGFR. There were no significant differences detected between conventional FAs and cellular FAs, except for PIK3CA and MAP3K1. TERT promoter alterations were most optimal in discriminating between FAs and benign PTs. Our study affirms the role of sequencing and key mutations that may assist in refining diagnoses of these lesions.

Diagnostic concordance of phyllodes tumour of the breast

AIMS

Phyllodes tumours (PT) are rare and distinct breast tumours, which span a morphological continuum. Classification into benign, borderline and malignant categories reflects their biology and clinical behaviour and is essential to guide management. This study aims to assess the diagnostic agreement of PT using the UK National Health Service Breast Screening Programme (NHSBSP) breast pathology external quality assurance (EQA) scheme data.

METHODS AND RESULTS

Twenty-six PTs were identified in the EQA scheme, which were diagnosed by an average of 607 participants/circulation. Data on diagnostic categories were collected and representative slides were reviewed. The level of concordance between reporting pathologists was assessed. There were 14 benign, six borderline and six malignant PT. The overall rate of diagnosis agreement was 86% when analysed as benign lesions, borderline PT and malignant lesions, which decreased to 79% when diagnosed as PT (irrespective of grade) and to 63% when the diagnosis was further refined to PT categories (benign, borderline and malignant PTs). The highest agreement rate was observed in malignant PT (86%) and the lowest in borderline PT (42%). Malignant heterologous elements, stromal overgrowth and leaf-like architecture are features associated with higher concordance rates. Lower-priority features were stromal expansion, clefting and multinodularity.

CONCLUSION

The concordance of PT diagnosis, as an entity, is high, but its classification into benign, borderline and malignant has variable agreement levels, with borderline tumours having the lowest concordance rate. More research to refine the diagnostic criteria for categorisation of PT is warranted to improve concordance between pathologists.

Fibroepithelial Lesions (FELs) of the Breast: Is Routine Excision Always Necessary?

BACKGROUND

When needle core biopsies (NCBs) of the breast reveal fibroepithelial lesions (FELs), excision is often performed to rule out a phyllodes tumor (PT), despite low malignancy rates. Consequently, the natural history of observed FELs is not well described. We analyzed the malignancy risk in excised FELs and the natural history of FELs undergoing active surveillance (AS).

METHODS

We retrospectively studied the pathology and imaging records of 215 patients with FELs (n = 252) diagnosed on NCB. Incidence of growth was determined by Kaplan-Meier method.

RESULTS

Of 252 FELs, 80% were immediately excised and 20% underwent AS. Of the excised FELs, 198 (98%) were benign: fibroadenoma (FA) or benign breast tissue in 137 (68%), benign PT in 59 (29%), or LCIS in 2 (1%). Borderline PT or malignant lesions were found in 4 (2%). On ultrasound, malignant and borderline PTs were larger than benign lesions [median 3.9 vs 1.3 cm, p = 0.006]. Fifty FELs underwent AS, with a median follow-up of 17 (range 2-79) months. The majority remained stable or decreased in size: at 2 years, only 35% increased in volume by ≥ 50%. Of those tumors undergoing AS that were later excised (n = 4), all were benign.

CONCLUSIONS

Almost all FELs (98%) were benign on surgical excision, and the majority undergoing AS remained stable, with benign pathology if later excised. Most FELs on NCB can be safely followed with US, with surgery reserved for patients with FELs that are large, symptomatic, or growing. This could spare most women with FELs unnecessary surgery.

Fibroepithelial lesions revisited: implications for diagnosis and management

Fibroepithelial lesions of the breast, comprising the fibroadenoma and phyllodes tumour, are a unique group of neoplasms that share histological characteristics but possess different clinical behaviour. The fibroadenoma is the commonest benign breast tumour in women, while the phyllodes tumour is rare and may be associated with recurrences, grade progression and even metastasis. The diagnosis of fibroadenoma is usually straightforward, with recognised histological variants such as the cellular, complex, juvenile and myxoid forms. The phyllodes tumour comprises benign, borderline and malignant varieties, graded using a constellation of histological parameters based on stromal characteristics of hypercellularity, atypia, mitoses, overgrowth and the nature of tumour borders. While phyllodes tumour grade correlates with clinical behaviour, interobserver variability in assessing multiple parameters that are potentially of different biological weightage leads to significant challenges in accurate grade determination and consequently therapy. Differential diagnostic considerations along the spectrum of fibroepithelial tumours can be problematic in routine practice. Recent discoveries of the molecular underpinnings of these tumours may have diagnostic, prognostic and therapeutic implications.

Ki67 and P53 Expression in Relation to Clinicopathological Features in Phyllodes Tumour of the Breast

OBJECTIVE

Phyllodes tumour (PT) is a rare fibroepithelial neoplasm of the breast that carries a risk of malignancy. Histopathological examination remains a gold standard for diagnosis. The usage of the immunohistochemical markers of Ki67 and p53 acts as a supplement method, particularly for the malignant PT. We aim here to study the expression of these markers in PT and to see their relation to the tumour grading.

METHODOLOGY

We conducted a retrospective cross-sectional study on 57 archived formalin-fixed paraffin-embedded tissue blocks of PT from the years 2015 to 2018 from two hospitals in East Coast Malaysia. The histopathological examination and immunohistochemical stain for Ki67 and p53 were analysed.

RESULTS

There was an association between clinical descriptive data of skin changes, lump size of more than 3 cm, cytological atypia, stromal hypercellularity, mitosis and immunohistochemistry with the clinical diagnosis of PT. Both marked expression of Ki67 and p53 were seen in borderline and malignant PT. Our study showed that in the presence of high mitotic figures, marked expression of Ki67 was only seen in cases of malignant PT.

CONCLUSION

We found a significant association of Ki67 and p53 expressions, high mitosis and other descriptive histopathological features in malignant PT. Further study with larger sample size is recommended to predict tumour grade and prognosis as well as the disease-free survival of the tumour. 
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Accuracy of p53 and ki-67 in the graduation of phyllodes tumor, a model for practical application

Background

The accurate graduation of a phyllodes tumor (PT) is critical for effective treatment as it allows correct surgical management, and avoids inadequate excision for malignant or borderline PT, or surgical overtreatment in benign PT. PTs of the breast are notoriously difficult to classify, and reliable differentiation of a benign PT from a borderline or malignant PT can be problematic, especially among relatively inexperienced pathologists. Although several authors acknowledge a strong relationship between the immunohistochemical expression of p53 and Ki-67 and the histopathological grade of PT—with potential impact on diagnostic accuracy—the literature lacks consensus about which cutoff defines a positive index test. The objective of this study is to establish a practical application score that increases the graduation accuracy of PT through the appropriate use of these auxiliary methods.

Methods

A retrospective study cohort of 146 pathology reviewed PTs surgically removed between January 2000 and December 2015. The Ki-67 test was considered positive if > 10% of neoplastic cells showed nuclear staining. The p53 test was considered positive if > 10% of neoplastic nuclear cells showed nuclear staining in a moderate or strong intensity.

Results

Of the 146 PT cases reviewed, 110 were classified as benign, 16 as borderline, and 20 as malignant. The correlation between age and size with benign, borderline, and malignant subgroups was statistically significant (p < 0.001). Significance was observed in the expression of both Ki-67 and p53 in the comparison of benign, borderline, and malignant PT with p < 0.001 and a 95% confidence interval (CI). When correlating the presence of positivity in either of the two index tests with the diagnosis of borderline or malignant PT, we reached a sensitivity of 100% and a specificity of 91.8 (p < 0.001; 95% CI).

Conclusion

We propose a practical methodology to achieve an accurate grade of PT, based on clearly defined and easy to apply cutoffs of a simple immunohistochemical panel of Ki-67 and p53. A PT positive for either of the index tests should be graded as borderline or malignant, so pathologists can use this test to improve accuracy. We hope this new approach might provide the basis for the development of standardization in using p53 and Ki-67 for grading PT.

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.

Expression of biomarkers in the AKT pathway correlates with malignancy and recurrence in phyllodes tumours of the breast

AIMS

Phyllodes tumours (PTs) of the breast are uncommon fibroepithelial neoplasms with the potential to recur and metastasise. Apart from histological grading, the expression of biological markers and its relationship with tumour behaviour have been topics of interest. The phosphatidylinositol 3-kinase (PI3K)-AKT pathway regulates diverse biological functions, and is one of the most frequently deregulated pathways in cancers. Little is known of PI3K-AKT pathway alteration in PT. We aim to investigate the alterations in different component of AKT pathway in PTs.

METHODS AND RESULTS

This study investigated the expression of four biological markers involved in this pathway (PTEN, INPP4B, PI3KCA and pAKT) in 134 PTs by the use of immunohistochemistry. According to an immunoscore incorporating staining intensity and proportion, low epithelial INPP4B expression (P = 0.045) was associated with recurrence. A trend of association was found for low epithelial PTEN expression with recurrence (P = 0.090). Interestingly, low epithelial INPP4B expression was also associated recurred tumours (P = 0.043). Stromal PI3KCA expression (P = 0.016) and pAKT expression (P = 0.006) were found to be correlated with increased histological grade, but an opposite trend was seen for stromal INPP4B expression (P = 0.018). In addition, epithelial and stromal PTEN expression, PI3KCA expression and pAKT expression showed strong correlations with each other (P ≤ 0.001).

CONCLUSIONS

These findings indicate that alterations in AKT pathway activation may correlate with malignant transformation and recurrence in PT. Low epithelial INPP4B/PTEN expression is associated with shorter recurrence-free survival. These observations suggest that the pathway may play a crucial role in the biological behaviour and progression of PT, and assessing the expression of this pathway may be of value in diagnosis, grading, prognostication, and management.

Magnetic resonance imaging of fibroadenoma-like lesions and correlation with Breast Imaging-Reporting and Data System and Kaiser scoring system

Background

Multiple breast lesions resembling fibroadenomas are a common imaging finding in patients presenting to the mammography unit at Dr George Mukhari Academic Hospital in the North-West district of Tshwane, South Africa. Patients often present with multiple lesions, up to 20 lesions per breast. These lesions often have atypical features on ultrasound and/or a clinical history of growth is commonly given. Phyllodes tumours may be indistinguishable from fibroadenomas and breast cancers may on occasion present with benign features, which can lead to misdiagnosis. Breast magnetic resonance imaging (bMRI) evaluation of lesions resembling fibroadenomas may improve accurate assessment and identification of lesions requiring biopsy.

Objectives

To assess the reliability of bMRI to characterise lesions resembling fibroadenomas on ultrasound, using the Breast Imaging-Reporting and Data System (BI-RADS) and Kaiser scoring systems with histopathological correlation.

Method

A quantitative, prospective, investigative study was performed with a sample size of 100 breast lesions among a total of 35 patients at Dr George Mukhari Academic Hospital. Patients were recruited after a breast ultrasound investigation revealed lesions resembling fibroadenomas, but with an indication for ultrasound-guided biopsy, for example, very large size, atypical features on ultrasound or a history of recent growth. The bMRI was performed prior to the ultrasound-guided breast biopsies. Three investigators independently evaluated the bMRI and applied BI-RADS descriptors to each lesion. The Kaiser score was then calculated for each lesion. Statistics were calculated using Pearson’s and Spearman’s coefficients for inter-reader variability, kappa scores for BI-RADS and Kaiser score correlation with histology.

Results

Evaluation with bMRI, BI-RADS and the Kaiser scoring system showed statistically significant correlation with each other and with histopathology results for each lesion. There was statistically significant agreement among the investigators regarding the interpretation of the lesions and allocation of appropriate BI-RADS scores.

Conclusion

Multiple lesions resembling fibroadenomas can be evaluated with bMRI when multiple breast biopsies would not be feasible. With a good imaging protocol and technique, adequate interpretation skills by the radiologist and the use of the Kaiser scoring system, an accurate diagnosis can be achieved.

Development of a Management Algorithm for the Diagnosis of Cellular Fibroepithelial Lesions From Core Needle Biopsies

Purpose. Surgical excision is recommended for complete evaluation of cellular fibroepithelial lesions identified from core needle biopsy. The purpose of this study was to determine factors associated with phyllodes tumor among cellular fibroepithelial lesions from core biopsies and develop a scoring system to predict the risk of phyllodes tumor. Methods. We retrospectively reviewed clinical data of 169 breast lesions that were diagnosed as cellular fibroepithelial lesions from core needle biopsy at the Seoul National University Bundang Hospital between March 2005 and January 2013. The clinical, histopathologic, and radiologic characteristics were compared between phyllodes tumors and fibroadenomas during the final diagnosis after surgical excision. Results. Of the 169 lesions, 17 were observed and 152 were surgically removed. After excision, final pathology revealed 60 (39.5%) fibroadenomas and 92 (60.5%) phyllodes tumors. Multivariate analysis demonstrated that age (≥40 years), stromal overgrowth, and stromal cellularity were independent factors associated with phyllodes tumors. A scoring system was developed based on a multivariate logistic regression model, and the area under the receiver operating characteristic curve was 0.828 (95% confidence interval = 0.763-0.893). Conclusion. The scoring system will help clinicians make appropriate treatment for patients with cellular fibroepithelial lesions on core needle biopsy.

Interobserver variation in the diagnosis of fibroepithelial lesions of the breast: a multicentre audit by digital pathology

Aim

Fibroepithelial lesions (FELs) of the breast span a morphological continuum including lesions where distinction between cellular fibroadenoma (FA) and benign phyllodes tumour (PT) is difficult. The distinction is clinically important with FAs managed conservatively while equivocal lesions and PTs are managed with surgery. We sought to audit core biopsy diagnoses of equivocal FELs by digital pathology and to investigate whether digital point counting is useful in clarifying FEL diagnoses.

Method

Scanned slide images from cores and subsequent excisions of 69 equivocal FELs were examined in a multicentre audit by eight pathologists to determine the agreement and accuracy of core needle biopsy (CNB) diagnoses and by digital point counting of stromal cellularity and expansion to determine if classification could be improved.

Results

Interobserver variation was high on CNB with a unanimous diagnosis from all pathologists in only eight cases of FA, diagnoses of both FA and PT on the same CNB in 15 and a ‘weak’ mean kappa agreement between pathologists (k=0.36). ‘Moderate’ agreement was observed on CNBs among breast specialists (k=0.44) and on excision samples (k=0.49). Up to 23% of lesions confidently diagnosed as FA on CNB were PT on excision and up to 30% of lesions confidently diagnosed as PT on CNB were FA on excision. Digital point counting did not aid in the classification of FELs.

Conclusion

Accurate and reproducible diagnosis of equivocal FELs is difficult, particularly on CNB, resulting in poor interobserver agreement and suboptimal accuracy. Given the diagnostic difficulty, and surgical implications, equivocal FELs should be reported in consultation with experienced breast pathologists as a small number of benign FAs can be selected out from equivocal lesions.

A Diagnostic Approach to Fibroepithelial Breast Lesions

Fibroepithelial breast lesions encompass a heterogeneous group of neoplasms that range from benign to malignant, each exhibiting differing degrees of stromal proliferation in relation to the epithelial compartment. Fibroadenomas are common benign neoplasms that may be treated conservatively. Phyllodes tumors are relatively rare lesions, and classified as benign, borderline, or malignant based on histologic evaluation of various parameters. The diagnostic interpretation of "gray-zone" fibroepithelial lesions often imposes formidable demands on a pathologist's skills. This article offers practical recommendations for the diagnostic workup of these lesions, including the appropriate utilization of ancillary investigations and the approach to core needle biopsies.

Validation of the Singapore nomogram for outcome prediction in breast phyllodes tumours in a large patient cohort

Aims

To validate the Singapore nomogram for outcome prediction in breast phyllodes tumours in a large cohort of Singaporean patients, as previous validation studies were conducted on small numbers of patients. We also investigate the association of fibroadenomas and phyllodes tumours within a subset of our cohort.

Methods

Histological parameters, surgical margin status and clinical follow-up data of 259 women diagnosed with phyllodes tumours were analysed. Patients with concurrent malignant or premalignant disease were excluded from the validation to minimise confounding influences. Biostatistics modelling was performed, and the concordance between predicted and observed survivals was calculated. The association between fibroadenomas and phyllodes tumours was quantified in a subset of the women.

Results

Phyllodes tumours with higher number of mitoses, stromal overgrowth and positive surgical margins were found to be associated with greater risk of clinical recurrence. Patients with a higher nomogram score had a significantly higher risk of developing relapse. Forty out of 78 (51.3%) of the subset of phyllodes cases reviewed showed either fibroadenoma-like areas within the phyllodes tumours or concurrent fibroadenomas in the ipsilateral or contralateral breast.

Conclusions

The Singapore nomogram is useful in predicting outcome in breast phyllodes tumours when applied to a large cohort of Singaporean women.

Fibroepithelial lesions; The WHO spectrum

Fibroepithelial lesions of the breast comprise a morphologically and biologically heterogeneous group of biphasic tumors with epithelial and stromal components that demonstrate widely variable clinical behavior. Fibroadenomas are common benign tumors with a number of histologic variants, most of which pose no diagnostic challenge. Cellular and juvenile fibroadenomas can have overlapping features with phyllodes tumors and should be recognized. Phyllodes tumors constitute a spectrum of lesions with varying clinical behavior and are graded as benign, borderline or malignant based on a set of histologic features according to recommendations by the World Health Organization (WHO). Recent developments have significantly expanded our understanding of the pathogenesis of fibroepithelial lesions, highlighting fibroadenomas as true neoplasms and underscoring a commonality with phyllodes tumors in the form of recurrent MED12 exon 2 mutations. In addition, sequencing studies have elucidated pathways associated with phyllodes tumor progression. Accurate diagnosis and grading of phyllodes tumors are important for patient management and prognosis, as grade broadly correlates with increasing local recurrence risk, and essentially only malignant tumors metastasize. However, classification of fibroepithelial lesions in many cases remains challenging on both core biopsy and excision specimens. A commonly encountered problem at the benign end of the spectrum is the distinction of benign phyllodes tumor from cellular fibroadenoma, which is largely due to the subjective nature of histologic features used in diagnosis and histologic overlap between lesions. Grading is further complicated by the requirement to integrate multiple subjective and ill-defined parameters. On the opposite end of the histologic spectrum, malignant phyllodes tumors must be distinguished from more common metaplastic carcinomas and from primary or metastatic sarcomas, which can be especially difficult in core biopsies. Immunohistochemistry can be useful in the differential diagnosis but should be interpreted with attention to caveats. This review provides an overview and update on the spectrum of fibroepithelial lesions, with special emphasis on common problems and practical issues in diagnosis.

Phyllodes Tumor of the Breast: Histopathologic Features, Differential Diagnosis, and Molecular/Genetic Updates

CONTEXT

-Phyllodes tumor (PT) of the breast is a rare fibroepithelial neoplasm with risks of local recurrence and uncommon metastases. The classification proposed by the World Health Organization for PTs into benign, borderline, and malignant is based on a combination of several histologic features. The differential diagnosis between PT and fibroadenoma and the histologic grading of PT remain challenging. In addition, the molecular pathogenesis of PT is largely unknown.

OBJECTIVE

-To provide an updated overview of pathologic features, diagnostic terminology, and molecular alterations of PT.

DATA SOURCES

-Current English literature related to PT of the breast.

CONCLUSIONS

-Phyllodes tumor shows a wide spectrum of morphology. There are no clearly distinct boundaries between PT and fibroadenoma. Strict histologic assessment of a combination of histologic features with classification can help to achieve the correct diagnosis and provide useful clinical information. The genomic landscapes of PT generated from genomic sequencing provide insights into the molecular pathogenesis of PT and help to improve diagnostic accuracy and identify potential drug targets in malignant PT.

First ultrasound diagnosis of BI-RADS 3 lesions in young patients: Can 6-months follow-up be sufficient to assess stability?

OBJECTIVES

To evaluate the outcome of repeated short-term follow-up with ultrasound in no high-risk young patients with a BI-RADS3 lesion at first examination.

METHODS

In this IRB-approved study 492 women, aged 18-34 years (mean±standard deviation, 28±4.5years) with first breast ultrasound examination in 2012-2014 were retrospectively evaluated. Inclusion criteria were: at least one BI-RADS3 lesion and (a) biopsy/surgical excision or (b) follow-up of at least 18 months (including a 6-month follow-up). BI-RADS category assigned during follow-up and pathologic findings in cases undergoing biopsy/surgical excision were collected. At the 6- and 18-month follow-up the recommended biopsy rates (RBR) and the corresponding positive predictive value (PPV) were calculated.

RESULTS

In 97 patients, 151 BI-RADS3 lesions were identified. Biopsy/surgical excision was initially performed in 25/151 (16.5%) lesions. After 6-month, category was downgraded to BI-RADS1/2 in 23/126 (15.3%) and upgraded to BI-RADS4 in 9/126 lesions (7.1%). Pathological diagnosis of these lesions was fibroadenoma in 5 and benign phyllodes tumor in 4 cases (RBR 7%, PPV_bio 44.4%). After 18-month one lesion was classified BI-RADS4 and pathological diagnosis was fibroadenoma (RBR 1.1%, PPV_bio 0%).

CONCLUSIONS

Our preliminary data show that follow-up imaging performed after 18 months from a first BI-RADS3 diagnosis does not affect clinical treatment and 6-month follow-up may be sufficient to assess the stability of probably benign lesions.

Contemporary indications for diagnostic open biopsy in women assessed for screen-detected breast lesions: A ten-year, single institution series of 814 consecutive cases

PURPOSE

In contemporary practice, 5% of women with non-malignant needle biopsies of screen-detected lesions still require diagnostic open biopsy (OBx). Our aims are to (i) capture a snapshot of the contemporary indications for OBx in screen-detected lesions; (ii) determine upgrade rates to malignancy (DCIS or invasive cancer); (iii) identify indications with sufficiently low upgrades to justify avoidance of OBx and (iv) propose plausible non-surgical alternatives.

METHODS

Between Jan 2005 and Dec 2014, women assessed for a screen-detected lesion and recommended for OBx are included. We retrieved patient, imaging, biopsy and final pathology or follow-up data.

RESULTS

814 lesions, mean diameter 16.7 mm, microcalcifications in 353 (43.4%) cases, lesions other than calcifications in 461 (56.6%), mean patient age 58.4 yrs, are included. Surgery was performed in 98.2% cases. Imaging follow-up (1-6.5 yrs) is available in 13 of 15 remaining cases. 27 indications for OBx were identified, with a prevalence of 0.3-13.9%. Borderline lesions (BL) comprised 64% of OBx indications, amongst which atypical ductal hyperplasia was the most prevalent at 13.9%, followed by papillary lesions, radial scars, flat epithelial atypia and lobular neoplasia. Imaging factors contributed 26.3% of OBx. In 9.8% of cases, NCB was not performed due to client, technical or cytologic factors. Overall, 261(32.1%) lesions were malignant at OBx. Upgrade rates varied from 0 to 100%, depending on the specific indication for OBx.

CONCLUSIONS

Surgical biopsy remains a valuable method of last resort for breast cancer diagnosis but strategies to limit benign breast surgery merit attention as a public health issue.

Diagnostic performance of core needle biopsy in identifying breast phyllodes tumors

BACKGROUND

A retrospective analysis of diagnoses was performed in patients with phyllodes tumors of the breast (PTB) who received preoperative core needle biopsy (CNB) and had breast surgery at Fudan University Shanghai Cancer Center from January 1, 2002 to April 1, 2013. The resulting data allowed us to compare the accordance between CNB and excision diagnoses of PTB patients and evaluate the accuracy of CNB in preoperative diagnosis.

METHODS

Data from 128 patients with PTB who had undergone preoperative CNB and breast surgery were retrospectively analyzed. We reviewed the medical history, clinical follow-up data, and CNB diagnostic data. A diagnostic test was used to evaluate the sensitivity and specificity of CNB in diagnosing benign, borderline, and malignant phyllodes tumors.

RESULTS

The accuracy of CNB for diagnosing PTB was 13.3% (17/128). Of the remaining patients, 98 (75.5% of the PTB patients) were diagnosed with fibroadenoma or fibroepithelial lesions. The sensitivity of CNB at diagnosing benign, borderline, and malignant phyllodes tumors were 4.9% (2/41), 4.2% (3/71), and 25.0% (4/16), respectively, whereas the corresponding specificity were 92.0%, 98.2%, and 100%, respectively. Some clinical features, such as large tumor size, rapid growth, or surgical history of fibroadenomas, were indicative of an increased possibility of PTB.

CONCLUSIONS

CNB provides a pathological basis for the preoperative diagnosis of PTB, but it has a poor accuracy and offers limited guidance for surgical decisions. Considering CNB along with multiple histologic features may improve the ability to accurately diagnose PTB. An integrated assessment using CNBs in combination with clinical data and imaging features is suggested as a reliable strategy to assist PTB diagnosis.

A five-gene reverse transcription-PCR assay for pre-operative classification of breast fibroepithelial lesions

Background

Breast fibroepithelial lesions are biphasic tumors and include fibroadenomas and phyllodes tumors. Preoperative distinction between fibroadenomas and phyllodes tumors is pivotal to clinical management. Fibroadenomas are clinically benign while phyllodes tumors are more unpredictable in biological behavior, with potential for recurrence. Differentiating the tumors may be challenging when they have overlapping clinical and histological features especially on core biopsies. Current molecular and immunohistochemical techniques have a limited role in the diagnosis of breast fibroepithelial lesions. We aimed to develop a practical molecular test to aid in distinguishing fibroadenomas from phyllodes tumors in the pre-operative setting.

Methods

We profiled the transcriptome of a training set of 48 formalin-fixed, paraffin-embedded fibroadenomas and phyllodes tumors and further designed 43 quantitative polymerase chain reaction (qPCR) assays to verify differentially expressed genes. Using machine learning to build predictive regression models, we selected a five-gene transcript set (ABCA8, APOD, CCL19, FN1, and PRAME) to discriminate between fibroadenomas and phyllodes tumors. We validated our assay in an independent cohort of 230 core biopsies obtained pre-operatively.

Results

Overall, the assay accurately classified 92.6 % of the samples (AUC = 0.948, 95 % CI 0.913–0.983, p = 2.51E-19), with a sensitivity of 82.9 % and specificity of 94.7 %.

Conclusions

We provide a robust assay for classifying breast fibroepithelial lesions into fibroadenomas and phyllodes tumors, which could be a valuable tool in assisting pathologists in differential diagnosis of breast fibroepithelial lesions.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-016-0692-6) contains supplementary material, which is available to authorized users.

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.

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.

Significant histologic features differentiating cellular fibroadenoma from phyllodes tumor on core needle biopsy specimens

OBJECTIVES

Cellular fibroepithelial lesions (CFELs) are a heterogeneous group of tumors encompassing cellular fibroadenoma (CFA) and phyllodes tumor (PT). Distinction between the two is challenging on core needle biopsy (CNB) specimens. The objective of this study was to evaluate histologic features that can help distinguish PT from CFA on CNB specimens.

METHODS

Records of all patients diagnosed with CFELs on CNB specimens with follow-up excision between January 2002 and December 2012 were retrieved. Histopathologic stromal features were evaluated on CNB specimens, including mitoses per 10 high-power fields (hpf), overgrowth, increased cellularity, fragmentation, adipose tissue infiltration, heterogeneity, subepithelial condensation, and nuclear pleomorphism.

RESULTS

Twenty-seven (42.2%) of 64 were diagnosed as PT (24 benign PTs and three borderline PTs) and 37 (57.8%) as CFA on excision. All features except for increased stromal cellularity were statistically significant. The average number of histologic features seen in PT and CFA was 3.9 and 1.4, respectively (odds ratio [OR], 7.27; 95% confidence interval [CI], 2.44-21.69; P = .0004). The average number of mitoses per 10 hpf was 3.0 for PT compared with 0.8 for CFA (OR, 2.14; 95% CI, 1.18-3.86; P = .01).

CONCLUSIONS

The presence of mitoses (three or more) and/or total histologic features of three or more on CNB specimens were the most helpful features in predicting PT on excision.

Differentiation between benign phyllodes tumors and fibroadenomas of the breast on MR imaging

PURPOSE

The purpose of this study was to determine the factors that contribute to the differentiation between phyllodes tumors (PTs) and fibroadenomas (FAs) on MR imaging.

MATERIALS AND METHODS

This retrospective study included 19 PTs and 18 FAs with ≥ 2 cm diameter. The presence or absence of a capsule and internal septum, the extent of lobulation, and the apparent diffusion coefficient (ADC) values were determined. The presence or absence of a cystic component, the time-intensity curve, and the signal intensity on delayed-phase contrast-enhanced T1WI were also evaluated in 31 patients (16 PTs and 17 FAs) who underwent a contrast-enhanced study.

RESULTS

Cystic components were seen in 10 of the 16 PTs (63%) and in 4 of the 17 FAs (24%; P=0.03). The PTs showed strong lobulation more frequently compared to the FAs (14/19 [74%] vs. 7/18 [39%], respectively; P=0.04). Though there was no significant difference, PT tended to be heterogeneous more frequently on the delayed phase of the contrast-enhanced T1WI compared to the FA (11/16 [69%] vs. 7/17 [41%], respectively). No significant difference was found in the other findings.

CONCLUSIONS

Although PTs and FAs show similar MR findings, the presence of a cystic component, strong lobulation, and heterogeneity on delayed-phase contrast-enhanced T1WI suggests a PT.

Phyllodes tumours of the breast diagnosed as B3 category on image-guided 14-gauge core biopsy: analysis of 51 cases from a single institution and review of the literature

AIMS

Image-guided 14-gauge (G) core biopsy (CB) has been shown to be an accurate method providing histological diagnosis of breast lesions. The purpose of this study was to evaluate the reliability of image-guided 14-G CB in the diagnosis of phyllodes tumours (PT) reported as B3 category and its accuracy in distinguishing this lesion from fibroadenomas (FA).

MATERIALS AND METHODS

The records of 10 000 image-guided 14-G CB of the breast performed from January 2001 to August 2011 at the Diagnostic Senology Unit of Careggi University Hospital were reviewed; 2554 (25.5%) were fibroepithelial lesions: 56 of them (2%) were diagnosed as PT and reported as B3 category. The database of the Pathological Anatomy Unit of Careggi University Hospital was then searched to verify the histological diagnosis after surgical excision. Fifty-one cases of PT diagnosed as B3 category in 51 women were included in the present study.

RESULTS

Of the 51 cases of PT diagnosed as B3 category on 14-G CB, 39 (76.5%) lesions were confirmed as PT on SE (30, 4 and 5 as benign, borderline and malignant PT respectively) with a PPV of 76.5%. Twelve lesions (23.5%) were diagnosed as FA after surgical excision.

CONCLUSIONS

Our study shows that 14-G CB is a valuable tool, in a preoperative setting, in diagnosing PT.

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

CONTEXT

The 2 main prototypes of fibroepithelial tumors of the breast include fibroadenoma and phyllodes tumor (PT). Although both tumors share some overlapping histologic features, there are significant differences in their clinical behavior and management. Phyllodes tumors have been further divided into clinically relevant subtypes, and there is more than one classification scheme for PT currently in use, suggesting a lack of consistency within different practices. Accurate differentiation between fibroadenoma and PT, as well as the grading of PT, may sometimes be challenging on preoperative core needle biopsy. Some immunohistochemical markers have been suggested to aid in the pathologic classification of these lesions.

OBJECTIVE

To discuss the salient histopathologic features of fibroepithelial tumors and review the molecular pathways proposed for the initiation, progression, and metastasis of PTs. Also, to provide an update on immunohistochemical markers that may be useful in their differential diagnosis and outline the practice and experience at our institution from a pathologic perspective.

DATA SOURCES

Sources included published articles from peer-reviewed journals in PubMed (US National Library of Medicine).

CONCLUSIONS

Fibroepithelial tumor of the breast is a heterogenous group of lesions ranging from fibroadenoma at the benign end of the spectrum to malignant PT. There are overlapping histologic features among various subtypes, and transformation and progression to a more malignant phenotype may also occur. Given the significant clinical differences within various subtypes, accurate pathologic classification is important for appropriate management. Although some immunohistochemical markers may be useful in this differential diagnosis, histomorphology still remains the gold standard.

Rapidly progressive multifocal phyllodes tumour of the breast: A case report and review of the literature

INTRODUCTION

Malignant transformation of a phyllodes tumour is a rare form of breast cancer, accounting for just 0.5% of all breast cancer cases.(1) PRESENTATION OF CASE: We report a case of a 49 year old female with rapidly progressive, multifocal disease. She initially presented with two giant fibroadenomas which were excised. She represented eight months post surgery with two new lesions in the same breast, one suspicious, one suggestive of fibroadenoma. Biopsy was borderline. Surgery was therefore scheduled for wide local excision. At localisation two weeks later, at least eight lesions were seen on ultrasound scan. Three were removed as histology was at this point unknown to conserve the breast. Histology revealed intermediate grade DCIS, benign Phyllodes and borderline/malignant phyllodes. She was scheduled for mastectomy and immediate Strattice reconstruction. An MRI was performed pre-operatively to ascertain extent of disease. Two weeks post localisation, 13 lesions were identified. The right breast was entirely unaffected. Surgery interval was three weeks and final histology revealed 18 lesions, ranging from fibroadenoma through to borderline/malignant phyllodes with an incidental papilloma.

DISCUSSION

This is the first report of such rapid progression of disease, with 16 new lesions, of varied histology, developing in just an eight week period.

CONCLUSION

This case highlights the difficulty of forming a clear diagnostic and therapeutic pathway in this highly variable disease. Arguments for over and under treating these patients remain but those with any borderline/malignant potential have to be removed as recurrence is both common and aggressive, with a clear surgical margin the only proven protective factor.