The variable histogenesis and biology of selected bland fibroblastic lesions of the breast - pitfalls in the differential diagnostics and optimal therapeutic approach (three case reports).

Presented are three casuistics of seemingly identical breast lesions which even by adopting advanced laboratory techniques may represent diagnostic challenge. Microscopic features of some bland spindle cell lesions of different histogenesis (epithelial or mesenchymal) are misleading and a potential source of unaware errors, which might affect optimal therapeutic strategy. In the setting of three diverse entities (low-grade spindle cell metaplastic carcinoma, desmoid fibromatosis and phyllodes tumor) is documented both demanding diagnostic algorithm and revealing molecular landscape on one side as well as evolving predictive/prognostic parameters on the other one. Close interdisciplinary cooperation is inevitable for accurate interpretation/understanding of revealed diagnostic facts which is required for adjustment of competent rational and individualized therapy.

Pneumothorax as a rare presentation in a case of phyllodes tumor of breast with cavitating lung metastasis.

ABSTRACT: The lung is the most common site of metastases in the case of phyllodes tumor of the breast followed by bone. However, pneumothorax as a presenting complaint in a patient of bilateral cavitating lung metastases from malignant phyllodes tumor of the breast has never been reported to our knowledge. We herein report a case of a 34-year-old female presenting with sudden onset of chest pain in already existing lung metastases who on imaging showed the development of bilateral pneumothorax. We should, therefore, be on the lookout for the potential development of spontaneous pneumothorax in such cases.

Relapsing malignant phyllodes tumour presenting as isolated acrometastases.

Malignant phyllodes tumours (PTs) are aggressive neoplasms with high rates of local recurrence and distant metastasis. With no known effective chemotherapy and no approved targeted therapy in the setting of metastatic disease, prognosis is limited with an often-relapsing course of disease. We report a case of a woman in her late 30s with a diagnosis of recurrent metastatic malignant PT who was found to have acrometastases of the malignant PT to the right distal index and small digits. We emphasise the potential for atypical patterns of metastases in patients with malignant PT and the need to recognise acrometastasis as an unusual but morbid manifestation of disease. Given the high growth rate of malignant PTs, the lack of systemic treatment options, and the ensuing distress for patients, prompt diagnosis and early intervention is crucial.

Validation Study of the Newly Proposed Refined Diagnostic Criteria for Malignant Phyllodes Tumor With 136 Borderline and Malignant Phyllodes Tumor Cases.

The World Health Organization (WHO) diagnostic criteria for malignant phyllodes tumor (MPT) may miss a significant number of MPTs with metastatic potential. New refined diagnostic criteria (Refined Criteria) for MPT were recently proposed. The aim of this study is to validate the Refined Criteria. This validation study included 136 borderline (borderline phyllodes tumor [BoPT]) and MPT cases that were not included in the initial study. We evaluated tumor classifications based on both the Refined Criteria and the WHO criteria. The Refined Criteria defines MPT when these criteria are met (1) stromal overgrowth with ≥ 1 feature(s) of marked stromal cellularity, marked stromal cytologic atypia, or ≥10 mitoses per 10 high-power fields (10 mitoses/10 HPFs) or (2) marked stromal cellularity with ≥1 feature(s) of marked stromal cytologic atypia, ≥10 mitoses/10 HPFs or permeative border. The WHO criteria require all 5 morphologic features (stromal overgrowth, permeative border, marked stromal cellularity, marked stromal cytologic atypia, and ≥10 mitoses/10 HPFs) for an MPT diagnosis. Using the Refined Criteria, none of the 61 BoPTs developed metastasis and 40.0% of the 75 MPTs developed metastases; local recurrence was seen in 11.5% BoPTs and 25.3% MPTs. Using the WHO criteria, 9.6% of the 94 BoPTs developed metastases and 50.0% of the 42 MPTs developed metastases; 14.9% of the BoPTs had local recurrence and 28.6% of the MPTs had local recurrence. Nine (30.0%) of the 30 tumors that developed distant metastases were diagnosed as BoPTs by the WHO criteria. When we combined the 75 MPTs from this validation cohort with the 65 MPT cases from the published data using the Refined Criteria, 50 (35.7%) of the 140 MPTs developed metastases, whereas 8 cases with metastases were <5 cm. In the univariate analysis with log-rank test, stromal overgrowth, marked stromal cellularity, marked stromal cytologic atypia, ≥10 mitoses/10 HPFs, presence of heterologous components other than liposarcomatous component, and presence of stromal necrosis were significantly associated with the risk of metastasis (all with P < 0.05). In multivariate analysis with Cox proportional hazard regression, stromal overgrowth and marked stromal cellularity were significantly associated with metastasis (both with P < 0.001). The Refined Criteria are superior to the WHO criteria in predicting the clinical outcomes of BoPTs and MPTs. Using the Refined Criteria, 35.7% of 140 patients with MPT developed metastases, whereas none (0%) of the patients with BoPT developed metastases. Patients with MPT have a high metastatic rate; these patients may benefit from systemic chemotherapy or targeted therapies. In contrast, patients with BoPT may be managed with complete local excision alone without chemotherapy.

Using the DNA Integrity Number to Analyze DNA Quality in Specimens Collected from Liquid-Based Cytology after Fine-Needle Aspiration of Breast Tumors and Lesions.

INTRODUCTION: Cancer genome analysis using next-generation sequencing requires adequate and high-quality DNA samples. Genomic analyses were conventionally performed using formalin-fixed paraffin-embedded sections rather than cytology samples such as cell block or smear specimens. Specimens collected from liquid-based cytology (LBC) have the potential to be sources of high-quality DNA suitable for genetic analysis even after long-term storage. METHODS: We collected breast tumor/lesion fractions from 92 residual LBC specimens using fine-needle aspiration (FNA) biopsy, including breast carcinoma (1 invasive carcinoma and 4 ductal carcinomas in situ), papillomatous lesion (5 intraductal papillomas), and fibroepithelial lesion (19 phyllodes tumors and 53 fibroadenomas) samples, and others (1 ductal adenoma, 1 hamartoma, 1 fibrocystic disease, and 7 unknown). DNA was extracted from all samples and subjected to DNA integrity number (DIN) score analysis. RESULTS: Average DIN score collected from 92 LBC specimens was significantly higher score. In addition, high-quality DNA with high DIN values (7.39 ± 0.80) was successfully extracted more than 12 months after storage of residual LBC specimens. CONCLUSION: Residual LBC specimens collected from FNA of the breast were verified to carry high-quality DNA and could serve as an alternate source for genetic analysis.

Integrating single-cell and spatial transcriptomes reveals COL4A1/2 facilitates the spatial organisation of stromal cells differentiation in breast phyllodes tumours.

BACKGROUND: Breast phyllodes tumours (PTs) are a unique type of fibroepithelial neoplasms with metastatic potential and recurrence tendency. However, the precise nature of heterogeneity in breast PTs remains poorly understood. This study aimed to elucidate the cell subpopulations composition and spatial structure and investigate diagnostic markers in the pathogenesis of PTs. METHODS: We applied single-cell RNA sequencing and spatial transcriptomes on tumours and adjacent normal tissues for integration analysis. Immunofluorescence experiments were conducted to verify the tissue distribution of cells. Tumour cells from patients with PTs were cultured to validate the function of genes. To validate the heterogeneity, the epithelial and stromal components of tumour tissues were separated using laser capture microdissection, and microproteomics data were obtained using data-independent acquisition mass spectrometry. The diagnostic value of genes was assessed using immunohistochemistry staining. RESULTS: Tumour stromal cells harboured seven subpopulations. Among them, a population of widely distributed cancer-associated fibroblast-like stroma cells exhibited strong communications with epithelial progenitors which underwent a mesenchymal transition. We identified two stromal subpopulations sharing epithelial progenitors and mesenchymal markers. They were inferred to further differentiate into transcriptionally active stromal subpopulations continuously expressing COL4A1/2. The binding of COL4A1/2 with ITGA1/B1 facilitated a growth pattern from the stroma towards the surrounding glands. Furthermore, we found consistent transcriptional changes between intratumoural heterogeneity and inter-patient heterogeneity by performing microproteomics studies on 30 samples from 11 PTs. The immunohistochemical assessment of 97 independent cohorts identified that COL4A1/2 and CSRP1 could aid in accurate diagnosis and grading. CONCLUSIONS: Our study demonstrates that COL4A1/2 shapes the spatial structure of stromal cell differentiation and has important clinical implications for accurate diagnosis of breast PTs.

Adenomyoepithelial adenosis mimicking phylloides: A diagnostic dilemma.

Benign proliferative breast diseases are well recognized in young females. Benign biphasic proliferation of epithelial and myoepithelial cells has been observed, among which adeno-myoepithelial adenosis is one of the rare morphologies published in the literature with the tendency to recur and poses a risk for low-grade malignant transformation. Here, we report a case of a young female who had a history of recurrent breast lump mimicking phyllodes tumor and eventually diagnosed as adeno-myoepithelial adenosis on histopathological examination. Benign proliferative breast diseases are well recognized in young females. Benign biphasic proliferation of epithelial and myoepithelial cells has been observed, among which adeno-myoepithelial adenosis is one of the rare morphologies published in the literature with the tendency to recur and poses a risk for low-grade malignant transformation. Here, we report a case of a young female who had a history of recurrent breast lump mimicking phyllodes tumor and eventually diagnosed as adeno-myoepithelial adenosis on histopathological examination.

Detailed DNA methylation characterisation of phyllodes tumours identifies a signature of malignancy and distinguishes phyllodes from metaplastic breast carcinoma.

Phyllodes tumours (PTs) are rare fibroepithelial lesions of the breast that are classified as benign, borderline, or malignant. As little is known about the molecular underpinnings of PTs, current diagnosis relies on histological examination. However, accurate classification is often difficult, particularly for distinguishing borderline from malignant PTs. Furthermore, PTs can be misdiagnosed as other tumour types with shared histological features, such as fibroadenoma and metaplastic breast cancers. As DNA methylation is a recognised hallmark of many cancers, we hypothesised that DNA methylation could provide novel biomarkers for diagnosis and tumour stratification in PTs, whilst also allowing insight into the molecular aetiology of this otherwise understudied tumour. We generated whole-genome methylation data using the Illumina EPIC microarray in a novel PT cohort (n = 33) and curated methylation microarray data from published datasets including PTs and other potentially histopathologically similar tumours (total n = 817 samples). Analyses revealed that PTs have a unique methylome compared to normal breast tissue and to potentially histopathologically similar tumours (metaplastic breast cancer, fibroadenoma and sarcomas), with PT-specific methylation changes enriched in gene sets involved in KRAS signalling and epithelial-mesenchymal transition. Next, we identified 53 differentially methylated regions (DMRs) (false discovery rate < 0.05) that specifically delineated malignant from non-malignant PTs. The top DMR in both discovery and validation cohorts was hypermethylation at the HSD17B8 CpG island promoter. Matched PT single-cell expression data showed that HSD17B8 had minimal expression in fibroblast (putative tumour) cells. Finally, we created a methylation classifier to distinguish PTs from metaplastic breast cancer samples, where we revealed a likely misdiagnosis for two TCGA metaplastic breast cancer samples. In conclusion, DNA methylation alterations are associated with PT histopathology and hold the potential to improve our understanding of PT molecular aetiology, diagnostics, and risk stratification. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Surgical Management and System Therapy of the Most Giant Known Malignant Metastatic Breast Phyllodes Tumor: A Case Report and Review of the Literature.

INTRODUCTION: Phyllodes tumors belong to uncommon fibroepithelial breast tumors with a range of biological behaviors. Phyllodes tumors are responsible for less than 1 percent of all neoplasms of the breast. CASE PRESENTATION: A 66-year-old woman presented to our Breastcancer Unit in March 2021 because of a huge mass of her left breast with bleeding out of a tumor necrosis. Five years ago in 2016, a benign phyllodes tumor was diagnosed externally. When we started the treatment, the tumor had a weight of 18.6 kg. CONCLUSION: We describe the surgical management and the systemic treatment of metastatic disease.

Malignant phyllodes tumour with lymph node metastasis: a diagnostic conundrum resolved by next generation DNA sequencing.

A malignant neoplasm with spindle cell and chondroid differentiation in the breast, metastatic to lymph node. In this context, a metaplastic carcinoma is typically favored given the exceptional nature of lymph node metastases in malignant phyllodes tumors (MPT). However, we demonstrate pathognomonic hotspot mutations in MED12 and the promoter of the TERT gene by targeted next-generation DNA sequencing, supporting a diagnosis of MPT.

Epithelial Carcinomas Arising within Phyllodes Tumours of the Breast: A Review of Their Pathological Characteristics.

Epithelial proliferation is a common feature of phyllodes tumours (PTs), but epithelial malignancy is rare. This review seeks to further our understanding of epithelial malignancy within PTs by analysing their histopathological characteristics in previously reported cases and providing an overview of studies on their pathological features. PubMed and DeepDyve were searched for case reports, case series, and literature reviews of in situ and invasive carcinoma within PTs. Only cases where the carcinoma was within the PT were included. Cases of synchronous carcinoma in the ipsilateral or contralateral breast were excluded. Ninety-eight cases of in situ or invasive carcinoma within a PT were identified. Across the grades of PTs, there was a similar proportion of invasive carcinomas compared to in situ lesions. Malignant PT correlates with a higher likelihood of epithelial malignancy, and molecular studies support a possible causal pathophysiological relationship. This higher likelihood may suggest interactions between malignant stroma and the transforming epithelium that could potentially play a significant role in the phenomenon, which remains to be elucidated. Encasement within a PT likely improves the prognosis of breast carcinoma due to earlier detection. The presence of carcinoma within a malignant PT has uncertain prognostic implications. Thorough sampling of all PTs is recommended for appropriate prognostication and management.

Malignant Phyllodes Tumor in a Pubertal Girl: A Report of a Case.

BACKGROUND: Malignant phyllodes tumor (MPT) is a rare breast disease that is extremely rare in children. A few cases of pediatric malignant phyllodes tumors have been reported, including some with a poor prognosis. CASE: A 14-year-old girl presented with a growing lump on her right breast. On the basis of imaging tests and a core needle biopsy, MPT was diagnosed, and right mastectomy was performed. The postoperative course was uneventful. SUMMARY AND CONCLUSION: MPT is an infrequent disease in adult females and is extremely rare in pubertal females. It occasionally shows rapid growth, metastasis, and recurrence with a poor prognosis. Early surgical resection is necessary to obtain a cure. When a rapidly growing breast tumor is observed in pubertal females, MPT should be considered.

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.

A case report of a patient with ductal carcinoma and a malignant phyllodes tumor in situ in 2 separate breasts.

RATIONALE: Breast malignant phyllodes tumors (MPT) are quite uncommon. It is rarely reported that they occur in conjunction with breast cancer. We detailed a case in which an MPT and ductal carcinoma in situ carcinoma occurred simultaneously in 2 different breasts. PATIENT CONCERNS: A 79-year-old female patient was seen for a rapidly growing lump in the upper left quadrant of her breast. The lump was described as huge, hard, irregular, and palpable. MRI of the breasts revealed a big mass in the left breast and a smaller lump in the right. DIAGNOSIS: Ductal carcinoma in situ with breast MPT. INTERVENTIONS: We performed a double mastectomy. Post-operative endocrine treatment was suggested. OUTCOMES: During the 18-month follow-up period, no signs of recurrence or metastasis were seen. The ultrasound examination of the chest wall showed no abnormality. Bilateral axillary and supraclavicular ultrasonography showed no lymphadenectasis and a CT scan of the lungs showed no suspicious cancer nodules. LESSONS: It is possible for MPT and ductal carcinoma in situ to occur simultaneously in different breasts. Surgeons need to integrate clinical observations, imaging tools, and patient history to make an early diagnosis. Before undergoing surgery, a thorough examination of both breasts is required.

Breast development and disorders in children and adolescents.

Breast masses are infrequently encountered in pediatric and adolescent populations. Most breast masses in children are benign entities arising from embryological defects which can be managed once breast development is complete. Diagnostic and management dilemmas arise when fibroepithelial lesions of the breast are seen in clinical practice. Differentiation between a fibroadenoma and a phyllodes tumor is important to guide management. Breast cancer in children under 18 years of age is extremely rare and invasive diagnostic testing and aggressive management is only recommended when clinical suspicion of malignancy is very high. Patient and caregiver counseling plays an important role in the management of these diseases. While adult-onset breast diseases have been studied very closely, there is a dearth of literature on pediatric breast anomalies. This review aims to provide a scoping overview of the available literature on benign, fibroepithelial, and malignant lesions of the breast in pediatric and adolescent populations to help guide physicians and surgeons with decision-making regarding the diagnosis and management of pediatric breast diseases.

Precise diagnosis of breast phyllodes tumors using Raman spectroscopy: Biochemical fingerprint, tumor metabolism and possible mechanism.

BACKGROUND: Breast fibroadenomas and phyllodes tumors are both fibroepithelial tumors with comparable histological characteristics. However, rapid and precise differential diagnosis is a tough point in clinical pathology. Given the tendency of phyllodes tumors to recur, the difficulty in differential diagnosis with fibroadenomas leads to the difficulty in optimal management for these patients. METHOD: In this study, we used Raman spectroscopy to differentiate phyllodes tumors from breast fibroadenomas based on the biochemical and metabolic composition and develop a classification model. The model was validated by 5-fold cross-validation in the training set and tested in an independent test set. The potential metabolic differences between the two types of tumors observed in Raman spectroscopy were confirmed by targeted metabolomic analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS: A total of 204 patients with formalin-fixed paraffin-embedded (FFPE) tissue samples, including 100 fibroadenomas and 104 phyllodes tumors were recruited from April 2014 to August 2021. All patients were randomly divided into the training cohort (n = 153) and the test cohort (n = 51). The Raman classification model could differentiate phyllodes tumor versus fibroadenoma with cross-validation accuracy, sensitivity, precision, and area under curve (AUC) of 85.58 % ± 1.77 %, 83.82 % ± 1.01 %, 87.65 % ± 4.22 %, and 93.18 % ± 1.98 %, respectively. When tested in the independent test set, it performed well with the test accuracy, sensitivity, specificity, and AUC of 83.50 %, 86.54 %, 80.39 %, and 90.71 %. Furthermore, the AUC was significantly higher for the Raman model than that for ultrasound (P = 0.0017) and frozen section diagnosis (P < 0.0001). When it came to much more difficult diagnosis between fibroadenoma and benign or small-size phyllodes tumor for pathological examination, the Raman model was capable of differentiating with AUC up to 97.45 % and 95.61 %, respectively. On the other hand, targeted metabolomic analysis, based on fresh-frozen tissue samples, confirmed the differential metabolites (including thymine, dihydrothymine, trans-4-hydroxy-l-proline, etc.) identified from Raman spectra between phyllodes tumor and fibroadenoma. SIGNIFICANCE AND NOVELTY: In this study, we obtained the molecular information map of breast phyllodes tumors provided by Raman spectroscopy for the first time. We identified a novel Raman fingerprint signature with the potential to precisely characterize and distinguish phyllodes tumors from fibroadenoma as a quick and accurate diagnostic tool. Raman spectroscopy is expected to further guide the precise diagnosis and optimal treatment of breast fibroepithelial tumors in the future.

Disseminated malignant phyllodes: Presentation after a decade.

Phyllodes tumors are rare biphasic fibroepithelial lesions of the breast and account for 0.3%-0.5% of primary breast tumors. Malignant phyllodes tumor has a 10%-26% risk of distant metastasis. The most common site of metastasis is lungs followed by bone and soft tissue. This is a rare case of a 42-year-old female with a previous history of malignant phyllodes tumor breast. She presented after 10 years with metastases to multiple sites including lung, abdominal wall, retroperitoneum, bone, and brain. These tumors have a poor overall survival. Accurate diagnosis and aggressive management of malignant phyllodes tumors can help in effective treatment at diagnosis and for close follow-up of the patients.

Benign Biphasic Tumors of the Mullerian Tract - a Mimic of Phyllodes Tumor. A Clinical-Pathologic Description of 21 Cases.

OBJECTIVE: A review of the clinical-pathologic characteristics and outcomes of biphasic polyps occurring in the female genital tract, not meeting the diagnostic criteria of Mullerian Adenosarcoma (MA). METHODS: An archival database search was run, after IRB approval, between 2001 and 2019, using terminology such as "Mullerian adenofibroma," "atypical Mullerian adenofibroma," "polypoid adenofibroma," and "atypical polyp with increased stromal cellularity." Two pathologists (JW and MRQ) reviewed all the retrieved cases and documented the morphologic features with particular emphasis on the presence of any features of Mullerian adenosarcoma. Follow-up data were also abstracted. RESULTS: Twenty-one cases, 12 cervical and 9 endometrial lesions, constituted the study cohort. Patients ranged from 26 to 64 years (median 49 years). On review, 20 of 21 of those cases showed Phyllodes-like architectural patterns. However, only one case showed all four features of MA, all of which were focal and inconspicuous. Follow-up (median duration of 5 years) did not document any recurrences in any of the 21 cases after excision. CONCLUSION: This series adds to the growing body of literature affirming the existence of benign biphasic Mullerian polyps encountered in the endometrium and cervix that fall short of the Mullerian adenosarcoma diagnosis.

Metastatic and Malignant Phyllodes Tumors of the Breast: An Update for Current Management.

Metastatic, malignant phyllodes tumor (PT) of the breast is a rare and aggressive neoplasm. Currently, there is no agreed upon consensus as to best management practices. A systematic review of literature was conducted investigating surgical, chemotherapeutic, and radiotherapeutic management for metastatic PT. Databases employed to identify articles included Embase, PubMed, and SAGE Journals. Diagnosis of metastatic PT has been of significant difficulty to radiologists as it is often confused with fibroadenomas. Surgically, metastatectomy has been correlated with increased overall survival (of 25.9 versus 9.9 months; P = .01). Radiotherapy has often been associated with palliation and pain control in metastatic, malignant neoplasia. However, one study showed that in malignant PT, radiation was associated with significantly lower rates of local recurrence (OR: 0.048 versus 0.209). Anthracycline containing chemotherapy regimens has been associated with improved overall survival (22.4 months versus 13.2 months; P = .040). Further research must be conducted into this rare malignancy to elucidate accurate diagnosis and care for patients with advanced metastatic or malignant phyllodes tumors.

Phyllodes Tumors of the Breast: Canadian National Consensus Document Using Modified Delphi Methodology.

PURPOSE: Phyllodes tumors are rare breast neoplasms with limited prospective data to guide treatment, leading to heterogeneous management of this disease. We developed National consensus statements using modified Delphi methodology including patients and practitioners across Canada. METHODS: Statements were developed based on a literature review. Two iterations of surveys were distributed with a planned virtual consensus meeting. Panelists were invited from surgery, radiation oncology, medical oncology, pathology, radiology, and plastic surgery. RESULTS: Twenty-three participants attended the virtual conference. One hundred statements regarding diagnostics, pathology, surgical planning, adjuvant therapies, recurrence, surveillance, and patient support were approved with an a priori defined consensus of ≥ 80%. Two tables on locoregional management were developed and approved. The management of borderline phyllodes tumors was a source of uncertainty, and recommendations reflect the lack of evidence in this rare presentation. CONCLUSION: A consensus document containing all approved statements for the care and management of phyllodes tumors was developed to help guide practice and future research.