Phyllodes tumours of the breast - differentiating features in core needle biopsy

Accuracy and Comparison of Core Needle Biopsy Diagnoses With Excision Specimen for Diagnosing Fibroepithelial Lesions of the Breast

Background Core needle biopsy (CNB) for fibroepithelial lesions (FELs) of the breast is commonly encountered by histopathologists. The distinction between fibroadenoma (FA) and phyllodes tumor (PT) can be challenging due to overlapping histological features and the limited nature of CNB material.  Objective This study aimed to assess the accuracy of CNB diagnosis of FA and PT by comparing it with a diagnosis on subsequent surgical excision specimen. Materials and methods A total of 166 cases of FELs of the breast who underwent CNB and subsequent surgical excision between January 2001 and December 2020 were included in our study. All microscopy glass slides were reviewed, and diagnosis confirmed. Results While 125 (75%) cases based on CNB received a definitive diagnosis of either fibroadenoma or PT, the remaining 41 (25%) cases were better classified on excision specimens and were descriptively diagnosed as fibroepithelial lesions on CNB. Diagnoses on CNB and on subsequent excision specimens were concordant in 113 (90.4%) cases. Among 12 cases that were discordant, three cases diagnosed as FA on CNB were upgraded to PT on excision specimens. Nine cases diagnosed as PT on CNB were diagnosed as FA on excision specimens. These included conventional, cellular, juvenile, and complex FA types. Three PTs, which were reported as FA on CNB, measured 6, 12.5, and 17.5 cm in the greatest dimension. Among 23 cases of PT which were further categorized on CNB, tumor categories changed on excision specimens in three cases. The diagnostic accuracy of CNB diagnosis was 90.4%. Conclusion CNB diagnosis showed good accuracy. PT diagnosis should be strongly considered in all tumors measuring >5 cm, especially those exceeding 10 cm. Cellular, juvenile, and complex FAs can be misdiagnosed as PT on CNB. Correlation with clinical and radiological findings can be helpful in establishing correct diagnosis.

De-escalating indications for excision when breast core needle biopsy returns fibroepithelial lesion-not further characterized

PURPOSE

Surgical excision is often performed to exclude phyllodes tumor (PT) when Core Needle Biopsy (CNB) of the breast returns fibroepithelial lesion-not further characterized (FEL-NFC). If imaging or CNB pathology features can be identified that predict a very low probability of borderline/malignant PT, thousands of women could be spared the expense and morbidity of surgical excisions.

METHODS

This retrospective cohort study includes 180 FEL-NFC from 164 patients who underwent surgical excisional biopsy.

RESULTS

The upgrade rate from FEL-NFC to benign PT was 15%, and to borderline/malignant PT 7%. Imaging features predicting upgrade to borderline/malignant PT included greater size (p = 0.0002) and heterogeneous echo pattern on sonography (p = 0.117). Histologic features of CNB predicting upgrade to borderline/malignant PT included "pathologist favors PT" (p = 0.012), mitoses (p = 0.014), stromal overgrowth (p = 0.006), increased cellularity (p = 0.0001) and leaf-like architecture (p = 0.077). A three-component score including size > 4.5 cm (Size), heterogeneous echo pattern on sonography (Heterogeneity), and stromal overgrowth on CNB (Overgrowth) maximized the product of sensitivity x specificity for the prediction of borderline/malignant PT. When the SHO score was 0 (72% of FEL-NFC) the probability of borderline/malignant PT on excision was only 1%.

CONCLUSION

The combination of size ≤ 4.5 cm, homogeneous echo pattern, and absence of stromal overgrowth is highly predictive of a benign excision potentially sparing most patients diagnosed with FEL-NFC the expense and morbidity of a surgical excision.

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.

Recurrence is Not Associated with Margin Status in Phyllodes Tumor

BACKGROUND

Phyllodes tumor (PT) is a rare fibroepithelial neoplasm of the breast. The proper extent of resection is still under debate. This study aimed to investigate the optimal surgical margin to prevent recurrence after surgery for PT and to evaluate risk factors for local recurrence (LR).

METHODS

Retrospective analysis of a prospective cohort database was performed. Patients who underwent curative surgery for PT at Seoul National University Bundang Hospital between July 2003 and February 2022 were reviewed.

RESULTS

Of the 439 patients included, 285 were benign, 129 were borderline, and 25 were malignant. There was no statistically significant difference in 5-year disease-free survival (DFS) between margin-negative and margin-involved patients (87.3% vs. 85.1%, p = 0.081). When patients were classified into groups, according to margin status, as conventional (≥ 1 cm from tumor), close (< 1 cm from tumor), or involved, 5-year DFS rates were also similar (100% vs. 86.9% vs. 85.1%, p = 0.170). In subgroup analysis for different histologic grades, 5-year DFS was not affected by margin involvement. In univariate analysis, large tumor size (> 5 cm; hazard ratio [HR] 2.857, p = 0.028) and infiltrative tumor border (HR 3.096, p = 0.012) were independent risk factors for LR. Further multivariate analysis found both factors to be prognostic.

CONCLUSIONS

Recurrence was not significantly influenced by margin status in all histological grades. In benign and borderline tumors, local excision without wide surgical margins could be sufficient, and watchful waiting could be an option for patients with positive margins after initial surgery.

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.

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.

Phyllodes Tumors: A Scoping Review of the Literature

PURPOSE

Phyllodes tumors are rare tumors of the breast, with most literature being retrospective with limited guidelines on the management of these patients. Scoping review was performed to highlight themes and gaps in the available literature.

METHODS

A scoping review of the literature was performed as per PRISMA-ScR guidelines with titles, abstracts, and full texts reviewed in duplicate. Data were abstracted and summarized in categories of diagnostics, surgical management, adjuvant therapies, treatment of recurrence, and surveillance. Quality assessment was performed for each paper.

RESULTS

The search identified 4498 references, 434 full-text papers were reviewed, and 183 papers were included. Ultrasound, magnetic resonance imaging, and core needle biopsy are valuable preoperative diagnostics tools. Pathology reporting should include stromal overgrowth, stromal cellularity, nuclear atypia, mitotic rate, borders, and presence of heterologous elements. Ki67 may have a role in grading and prognosticating. Breast conservation is safe in all grades of phyllodes but may be associated with increased local recurrence in malignant phyllodes. Surgical margins should depend on grade. Axillary node positivity rate is very low, even with clinically enlarged lymph nodes. Adjuvant radiation is a useful tool to decrease local recurrence in malignant phyllodes tumors, tumors > 5 cm, age < 45 years, close margins, and breast conservation. There is no evidence supporting adjuvant chemotherapy. Recurrence can be managed with repeat wide excision; however, mastectomy is associated with lower re-recurrence. Surveillance protocols are variable in the literature.

CONCLUSIONS

There is heterogeneity in the literature on phyllodes tumors. Consensus guidelines based on the literature will help provide evidence-based care.

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.

Rare case of gigantic ulcerating phyllodes tumour in developed country with a review of the literature

Phyllodes tumour (PT) is a rare type of fibroepithelial breast tumour that can present in a wide spectrum of biological behaviours, accounting for <1% of breast malignancies. Herein, we present a case of a rare gigantic ulcerating PT in a middle-aged woman from regional Western Australia, who presented with a rapidly growing right breast mass. Core biopsy showed spindle cell lesion with differentials being PT of at least borderline variety or metaplastic carcinoma. The ulcerations over the fungating tumour showed heavy growth of Staphylococcus aureus. The treating team subsequently proceeded to right total mastectomy with level 1 and 2 axillary clearance. This report emphasizes the rare presentation of PT, dilemma in investigations and the difficulties in managing non-compliant patient where treatment protocol needs to be modified.

Fibroepithelial Lesion Initially Believed to Be Fibroadenoma, but Interval Growth Consistent With Phyllodes Tumor

Fibroepithelial lesions of the breast are commonly encountered tumors comprised of stromal and epithelial components. Fibroadenoma and phyllodes tumor are both fibroepithelial lesions, but their management differs. Phyllodes tumor requires surgical excision, whereas fibroadenoma requires no further workup. Both have many overlapping histological features making it difficult to distinguish between a benign fibroadenoma versus the more aggressive phyllodes tumor. This case details a breast mass that was initially believed to be a fibroadenoma, but interval growth at one year follow up resulted in surgical excision with final pathology revealing phyllodes tumor.

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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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.

Re-excision or "wait and watch"-a prediction model in breast phyllodes tumors after surgery

Background

The prognosis of breast phyllodes tumors (PTs) largely depending on the pathological grading, which lacks objectivity. This study aimed to develop a nomogram based on clinicopathological features to evaluate the recurrence probability of PTs following surgery.

Methods

Data from 334 patients with breast PTs, who underwent surgical treatment at Sun Yat-sen Memorial Hospital from January 2005 to December 2014, were used to develop a prediction model. Additionally, data of 36 patients from Peking University Shenzhen Hospital (cohort 1) and data of 140 patients from Sun Yat-sen University Cancer Center (cohort 2) during the same period were used to validate the model. The medical records and tumor slides were retrospectively reviewed. The log-rank and Cox regression tests were used to develop a clinical prediction model of breast PTs. All statistical analyses were performed using R and STATA.

Results

Of all 334 patients included in the primary cohort, 224 had benign, 91 had borderline, and 19 had malignant tumors. The 1-, 3-, and 5-year recurrence-free survival was 98.5%, 97.9%, and 96.8%, respectively. Ultrasound-guided vacuum-assisted biopsy (UGVAB) is a non-inferior treatment application in benign PTs compared with open surgery [hazard ratio (HR), 2.38; 95% confidence interval (CI), 0.59–9.58]. Width of surgical margin, mitoses, and tumor border were identified as independent risk factors for breast PTs. A nomogram was developed based on these three variables. The C-index of internal and external validation was 0.71, 0.67 (cohort 1) and 0.73 (cohort 2), respectively.

Conclusions

The study model presented more concise and objective variables to evaluate the recurrence-free survival of patients after surgery, which can help deciding whether to do a re-excision or “wait and watch”.

Mammary mesenchymal and fibroepithelial lesions: An illustrated cytomorphologic update with differential diagnoses

The Uniform Approach to Breast Fine Needle Aspiration Biopsy was put forward by a learned group of breast physicians in 1997. This landmark manuscript focused predominantly on diagnosis and reporting of mammary epithelial lesions. Today, most American practitioners turn initially to core biopsy rather than aspiration biopsy for the first line diagnosis of solid breast lesions; however, recent efforts from the International Academy of Cytology have produced a system called the Standardized Reporting of Breast Fine Needle Aspiration Biopsy Cytology (colloquially labeled in 2017 as the "Yokohama System"), suggesting a new interest in breast fine needle aspiration (FNA), especially in resource limited settings or clinical practice settings with experienced breast cytopathologists. Fibroepithelial lesions of the breast comprise a heterogeneous group of biphasic tumors with epithelial and stromal elements. Mesenchymal lesions of the breast include a variety of neoplasms of fibroblastic, myofibroblastic, endothelial, neural, adipocytic, muscular, and osteo-cartilaginous derivations. The cytology of mesenchymal breast lesions is infrequently described in the literature and is mainly limited to case reports and small series. This illustrated review highlights the cytologic features of fibroepithelial and mesenchymal mammary proliferations and discusses differential diagnoses and histomorphologic correlates.

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.

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.

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.

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.

Phyllodes tumors of the breast: diagnosis, treatment and prognostic factors related to recurrence

Phyllodes tumors of the breast are rare tumor types that consist of 0.3-1.0% in all breast tumors. The naming and classification of breast phyllodes tumor have been debated for years. Based on the classification criteria modified by WHO in 2003, this review mainly introduced the clinicopathologic characteristics, pre-operational diagnosis and the treatment of breast phyllodes tumors, and also summarized the prognostic factors related to tumor recurrence.

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.

TERT promoter mutations are frequent and show association with MED12 mutations in phyllodes tumors of the breast

Background:

Phyllodes tumors are rare fibroepithelial neoplasms of the breast, which carry the potential risk of local recurrence and metastasis. Phyllodes tumors share several histological features with fibroadenomas, and no widely accepted markers for distinguishing these lesions have been identified.

Methods:

We analyzed molecular abnormalities related to telomere elongation in tumors, including TERT promoter mutations, as well as loss of expression of ATRX and DAXX, in a total of 104 phyllodes tumors and fibroadenomas.

Results:

Sequencing analyses showed that TERT promoter mutations were frequent in phyllodes tumors (30/46, 65%), but rare in fibroadenomas (4/58, 7%). Among phyllodes tumors, the mutations were more frequent in borderline tumors (13/15, 87%), but were also common in benign (9/18, 50%) and malignant tumors (8/13, 62%). Remarkably, all but one TERT promoter-mutated tumor also contained MED12 mutations, indicating that these mutations are strongly associated (P=8.4 × 10⁻⁶). Expression of ATRX and DAXX, as evaluated by immunohistochemistry, was retained in all tumors.

Conclusions:

Our observations suggest a critical role of TERT promoter mutations, in cooperation with MED12 mutations, in the development of phyllodes tumors. Because TERT promoter mutations are rare among fibroadenomas, their detection may be of potential use in discriminating between phyllodes tumors and fibroadenomas.

A Single-center Experience and Review of the Literature: 64 Cases of Phyllodes Tumors to Better Understand Risk Factors and Disease Management

Phyllodes tumors of the breast are rare fibroepithelial tumors that are characterized as benign, borderline, or malignant based on cellular characteristics such as stromal overgrowth and number of mitoses. Currently, there is a lack of consensus on risk factors and management of patients with phyllodes tumors, which has led to variation in treatment patterns as well as patient outcomes across many institutions. This study seeks to understand the clinicopathologic features, risk factors for local and metastatic recurrence, and clinical outcomes of patients with phyllodes tumors to better define optimal treatment patterns.

Phyllodes tumor diagnosed after ultrasound-guided vacuum-assisted excision: should it be followed by surgical excision?

Our aim was to retrospectively evaluate the results of ultrasound (US)-guided vacuum-assisted excision (US-VAE) of phyllodes tumors (PTs). A total of 41 PTs diagnosed at US-VAE followed by surgery (n = 27) or at least 2 y of US monitoring (n = 14) were included. By comparison of US-VAE pathology with surgical histology or follow-up US results, cases were divided into upgraded (malignant) and non-upgraded (benign) groups. These two groups were compared with respect to clinical, procedural and US features. Among 27 surgical cases, 2 (8.7%) of 23 benign PTs were upgraded to malignant PTs. The Breast Imaging Reporting and Data System category was retrospectively assigned as 4a (50%) or 4b (50%) in the upgraded group (n = 2) and 3 (64%) or 4a (36%) in the non-upgraded group (n = 39) (p = 0.018). Residual tumor was observed at the site of US-VAE in 15 of 27 surgical cases and 0 of 14 US follow-up cases (36.6%, 15/41). Given the rates of upgrade to malignancy (8.7%) and residual tumor (36.6%), PTs diagnosed after US-VAE should be surgically excised.

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.

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.

Phyllodes tumors of the breast: ultrasonographic findings and diagnostic performance of ultrasound-guided core needle biopsy

We evaluated ultrasonography (US) findings between benign and malignant phyllodes tumors and analyzed diagnostic performance of US-guided core needle biopsy (CNB) for phyllodes tumors. Surgically removed phyllodes tumors of 168 women were divided into two groups according to the benign and malignant (including borderline tumor) groups and 116 were benign and 52 were malignant. On US, the complex cystic echogenicity (p = 0.021), presence of cleft (p = 0.005) and higher final US assessment (p = 0.008) were more frequent in the malignant group. The sensitivity of CNB including fibroepithelial tumors was 67.9% (114/168) and the concordant rate between CNB and surgical excision was 82.1% (32/39) and 5.8% (3/52) in the benign and malignant group. Our results suggested that the US findings of complex cystic echogenicity, cleft, higher final US assessment were more frequent in malignant phyllodes tumors. The sensitivity of CNB was 67.9% (114/168) and malignant phyllodes tumors were rarely diagnosed as malignant by US-guided CNB.