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.

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.

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.

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.

"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.

Gene Expression Profiling of Fibroepithelial Lesions of the Breast.

Fibroepithelial lesions of the breast (FELs) are a heterogeneous group of neoplasms exhibiting a histologic spectrum ranging from fibroadenomas (FAs) to malignant phyllodes tumors (PTs). Despite published histologic criteria for their classification, it is common for such lesions to exhibit overlapping features, leading to subjective interpretation and interobserver disagreements in histologic diagnosis. Therefore, there is a need for a more objective diagnostic modality to aid in the accurate classification of these lesions and to guide appropriate clinical management. In this study, the expression of 750 tumor-related genes was measured in a cohort of 34 FELs (5 FAs, 9 cellular FAs, 9 benign PTs, 7 borderline PTs, and 4 malignant PTs). Differentially expressed gene analysis, gene set analysis, pathway analysis, and cell type analysis were performed. Genes involved in matrix remodeling and metastasis (e.g., MMP9, SPP1, COL11A1), angiogenesis (VEGFA, ITGAV, NFIL3, FDFR1, CCND2), hypoxia (ENO1, HK1, CYBB, HK2), metabolic stress (e.g., UBE2C, CDKN2A, FBP1), cell proliferation (e.g., CENPF, CCNB1), and the PI3K-Akt pathway (e.g., ITGB3, NRAS) were highly expressed in malignant PTs and less expressed in borderline PTs, benign PTs, cellular FAs, and FAs. The overall gene expression profiles of benign PTs, cellular FAs, and FAs were very similar. Although a slight difference was observed between borderline and benign PTs, a higher degree of difference was observed between borderline and malignant PTs. Additionally, the macrophage cell abundance scores and CCL5 were significantly higher in malignant PTs compared with all other groups. Our results suggest that the gene-expression-profiling-based approach could lead to further stratification of FELs and may provide clinically useful biological and pathophysiological information to improve the existing histologic diagnostic algorithm.

Phyllodes Tumor of the Bladder in a 2-Year-Old Boy - An Exceptional Finding.

Background: Breast phyllodes tumor has a distinct histologic appearance. There are no pediatric phyllodes tumors of the bladder in English literature reported. Case report: A 2-year-old boy presented with a urinary infection and obstructive urinary symptoms. A 3-cm slow-growing bladder mass revealed by repeated transabdominal ultrasonography was initially considered a ureterocele. Cystoscopic and laparoscopic exploration using pneumovesicum confirmed the diagnosis of a bladder neck tumor. Histologically, the features were of a benign phyllodes tumor, morphologically similar to those seen in breast tissue. The patient received no further treatment and showed no recurrence or metastasis. Conclusion: Phyllodes tumor can cause a pediatric bladder tumor.

[Pathological features and clinicopathological significance of TERT promoter mutation in breast fibroepithelial tumors without definite diagnosis].

Objective: To investigate the pathological features and the clinicopathological significance of TERT detection in those tumors that were difficult to diagnosis. Methods: A total of 93 cases of fibroepithelial tumors without definite diagnosis were collected from the Affiliated Hospital of Qigndao University between 2013 and 2021. The clinical details such as patients' age and tumor size were collected. All slides were re-reviewed and the pathologic parameters, including stromal cellularity, stromal cell atypia, stromal cell mitoses, and stromal overgrowth were re-interpreted. Sanger sequencing was used to detect TERT promoter status, and immunohistochemistry was performed to detect TERT protein expression. The relationship between TERT promoter mutation as well as protein expression levels and the clinicopathological parameters were also analyzed. Results: The patients' ages ranged from 30 to 71 years (mean of 46 years); the tumor size ranged from 1.2 to 8.0 cm (mean 3.8 cm). These tumors showed the following morphologic features: leafy structures in the background of fibroadenoma, or moderately to severely abundant stromal cells. The interpretations of tumor border status were ambiguous in some cases. The incidence of TERT promoter mutation was high in patients of age≥50 years, tumor size≥4 cm, and stromal overgrowth at ×4 or ×10 objective, and these clinicopathologic features were in favor of diagnosis of phyllodes tumors. TERT protein expression levels was not associated with the above clinicopathologic parameters and its promoter mutation status. Conclusions: The diagnostic difficulty for the breast fibroepithelial tumors is due to the difficulty in recognition of the leafy structures or in those cases with abundant stromal cells. A comprehensive evaluation combined with morphologic characteristics and molecular parameters such as TERT promoter may be helpful for the correct diagnosis and better evaluating recurrence risk.

[A Case of Giant Phyllodes Tumor Treated with Breast Reconstruction].

A 62-year-old woman was diagnosed with right breast tumor 2 years ago, which she refused to undergo surgery. The patient experienced a rapid enlargement of the mass over the past 1 month, and visited hospital. The patient was diagnosed with a borderline phyllodes tumor by needle biopsy. Her right breast was occupied by an 18 cm mass. We conducted tumor resection and immediate reconstruction with DIEAP flap. The pathological diagnosis was a malignant phyllodes tumor, and the postoperative radiation to the chest wall was performed. During a year and a half follow up, she has no recurrence and highly satisfied with the reconstructed breast. Phyllodes tumors may recur locally regardless of whether they are benign or malignant, and we need strict follow-up.

[Invasive Ductal Carcinoma within a Borderline Malignancy Phyllodes Tumor-A Case Report].

Phyllodes tumors are uncommon breast neoplasms that constitute 1-2% of breast malignancies. Invasive ductal carcinoma in the epithelial component of phyllodes tumor is very rare. When carcinoma is detected within the specimen, the management of treatment changes completely. We report a rare case of invasive ductal carcinoma arising in a giant borderline malignancy phyllodes tumor in a 51-year-old female patient. A painful 20 cm mass was found in her right breast, and a needle biopsy revealed fibroadenoma or benign phyllodes tumor, and a total mastectomy was performed. Pathological results showed that a borderline malignant phyllodes tumor coexisted with invasive ductal carcinoma. We explained that axillary surgery was necessary because invasive cancer was diagnosed after surgery, but the patient requested follow-up using images. Endocrine therapy was performed as postoperative adjuvant therapy, and the follow-up is underway without recurrence.

[A Case of a Malignant Phyllodes Tumor of the Breast with Osteogenic Sarcoma Which Repeated Local Recurrence].

The patient is a 39-year-old woman. At the age of 34, she recognized a 22 mm sized mass in the upper outer quadrant of her right breast, which was diagnosed as a fibroadenoma. 5 years later, the mass increased to 45 mm. We performed lumpectomy which led to a diagnosis of a malignant phyllodes tumor with osteogenic sarcoma. Since the resection margins were positive, we performed mastectomy in addition. Nine months after surgery, a 23 mm large mass appeared on the right fifth costal. Recurrence of malignant phyllodes was suspicious from cytological diagnosis and since thoracoabdominal CT showed no metastasis to other organs, we performed resection. Histological results were the same as the primary tumor. Two months more later, an 11 mm large mass revealed in the right anterior thoracic region. We performed resection again, which showed the same histological features as the primary tumor. Since malignant phyllodes tumors often recur in the early postoperative period, a close follow-up is recommended.

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.

Excision of breast fibroepithelial lesions: when is it still necessary?-A 10-year review of a regional centre.

PURPOSE: Fibroepithelial lesions (FEL) range from benign fibroadenoma (FA) to malignant phyllodes tumor (PT), but can be difficult to diagnose on core needle biopsy (CNB). This study assesses risk factors for phyllodes tumor (PT) and recurrence and whether a policy to excise FELs over 3 cm in size is justified. METHODS: Patients having surgery for FELs from 2009 to 2018 were identified. The association of clinical, radiology and pathological features with PT and recurrence were evaluated. Trend analysis was used to assess risk of PT based on imaging size. RESULTS: Of the 616 patients with FELs, 400 were identified as having FA on CNB and 216 were identified as having FEL with a comment of concern for phyllodes tumor (query PT, QPT). PT was identified in 107 cases; 28 had CNB of FA (7.0%), while 79 had QPT (36.6%). Follow-up was available for 86 with a mean of 56 months; six patients had recurrence of PT, all of whom had QPT on CNB. The finding of PT was associated with CNB of QPT, increasing age and size on multivariate logistic regression. All patients diagnosed with PT following CNB of FA had enlarging lesions with a mean size of 38.3 mm. CONCLUSIONS: Our data does not support routine excision of FELs based on size alone. All patients with QPT on CNB, regardless of size should consider excision due to high risk of PT and recurrence, and the decision to excise FAs to rule out PT should also consider whether the lesion is enlarging.

miR-140-3p is a potential differential biomarker in benign phyllodes tumors and fibroadenoma of the breast.

BACKGROUND: Benign phyllodes tumor (BPT) and fibroadenoma (FA) have some difficulties in differential diagnosis. BPT is often misdiagnosed as FA during the first operation and is not diagnosed until postoperative recurrence and reoperation. The intent of this research was to find and validate microRNAs (miRNAs) with significant differential expression between BPT and FA as novel potential differential biomarkers. METHODS: Tissue specimens from three BPT patients and three FA patients were selected to detect the expression of miRNAs by miRNA-Seq technique. Primary cells were extracted and cultured from fresh BPT and FA tissues by tissue-block culture. The expression of differentially expressed miRNA (DEmiRNA) was further verified by quantitative real-time polymerase chain reaction (qRT-PCR) in twelve BPT and eleven FA patient specimens as well as primary cells. Data with a P value < 0.05 were considered statistically significant. RESULTS: The miRNA-Seq results showed totally six DEmiRNA were identified, consisting of two downregulated genes and four upregulated genes in BPT. Further validation by qRT-PCR manifest that miR-140-3p was downregulated by approximately 70% in BPT. CONCLUSION: miR-140-3p could become potential differential biomarker for BPT and FA.

Fibroepithelial lesions of the breast: A review of recurring diagnostic issues.

Breast fibroepithelial lesions, which are composed of biphasic epithelial and stromal proliferations, comprise the fascinating spectrum of fibroadenomas and phyllodes tumours. Common difficulties surrounding their diagnosis include distinguishing between cellular fibroadenomas and benign phyllodes tumours, grading phyllodes tumours, classifying fibroepithelial lesions in paediatric patients, and handling surgical margins. Recent molecular advances have provided insights into the pathogenesis of fibroepithelial lesions and may offer diagnostic, prognostic, and therapeutic information. In this review, we briefly revisit the pathological features of fibroadenomas and phyllodes tumours, discuss common diagnostic dilemmas and management implications, and examine their key molecular characteristics.

Diagnosis and management of phyllodes tumours for the surgeon: An algorithm.

A Phyllodes Tumour (PT) is an uncommon fibroepithelial lesion, with three histological grades - benign, borderline and malignant. PTs cause significant challenges in diagnosis, management and prognostication. Recent publications have clarified the definitions and prognostication of PTs. Contemporary data currently challenge international guidelines on PT management. We performed an in-depth literature review to develop a best-practice management algorithm for PTs. Diagnostic recommendations are that neither current imaging techniques, nor fine-needle biopsies, can reliably diagnose a PT. Core needle biopsy is the optimal diagnostic technique. Indeterminate or suspicious lesions are recommended to undergo an excisional biopsy due to the inherently heterogeneous nature of PTs. Management guidelines are that benign PTs should be completely excised, although an involved margin is acceptable in select situations. Borderline PTs should have a clear margin on excision due to their higher risk of recurrence, as well as the potential for a recurrence to progress to a malignant PT. In malignant PTs, a margin of 3 mm is acceptable as there is no reduction in recurrence risk if margins are >3 mm. Routine axillary surgery is not indicated in PTs, with axillary surgery only indicated in a histologically-confirmed positive axilla. Adjuvant treatment recommendations are that borderline and malignant PTs should be discussed at MDT, with radiotherapy considered in both. Chemotherapy should be discussed in malignant PT patients. In summary, we have developed an up-to-date simple algorithm to guide the surgeon's management of patients diagnosed with PTs and reduce excessive surgery.

Malignant phyllodes tumor of the breast: a systematic review.

Phyllodes tumors (PT) are fibroepithelial neoplasms of the breast showing a peculiar leaf-like appearance. They account for 0.3 to 1% of all primary breast tumors and 2.5% of all fibroepithelial breast tumors. PT are classified into benign, borderline and malignant based upon their stromal morphology with a distribution of 60%, 20%, and 20%, respectively. Malignant PT of the breast constitute an uncommon challenging group of fibroepithelial neoplasms. They have a relatively high tendency to recur, although distant metastasis is uncommon, and nearly exclusive to malignant PT. Adequate surgical resection remains the standard approach to achieve maximal local control. Giant malignant PT are rare and a pose a diagnostic dilemma for pathologists, especially when comprised of sarcomatous elements. This review highlights the morphological features of PT detected in cytology and histology specimens and discusses diagnostic pitfalls and differential diagnosis.

[A Case of Breast Nodular Fasciitis Needed to Differentiate from Borderline Phyllodes Tumor].

A 28-year-old woman realized a left breast tumor. Mammography and ultrasonography revealed focal asymmetric density on the MI area(category 3)and a low-echoic 10 mm tumor with unclear boundaries. We performed an US-guided breast biopsy to confirm the diagnosis. The histopathological examination result suspected nodular fasciitis; however, borderline phyllodes tumor cannot be denied. Tumorectomy was performed under general anesthesia. The final histopathological examination revealed nodular fasciitis due to amplifying fibroblasts with irregular directions. Nodular fasciitis is a benign lesion and sometimes disappears spontaneously. Tumorectomy is often needed to confirm the diagnosis that cannot be identified by needle biopsy. We report a case of breast nodular fasciitis needed to differentiate from borderline phyllodes tumor.

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.