Phyllodes Tumor of the Breast: A Clinicopathological Evaluation of 55 Cases

Differential diagnosis of primary mesenchymal neoplasms of the breast

OBJECTIVE

While the majority of breast neoplasms originate from epithelial cells, a rare part of them originate from mesenchymal breast tissue. This study aims to present the histomorphological and clinicoradiological features of our series of primary mesenchymal breast tumors and to discuss the features of these tumors in light of the literature.

MATERIALS AND METHODS

Cases diagnosed as primary mesenchymal breast tumor in breast resection materials evaluated in our center between 2010 and 2023 were included.

RESULTS

Of the 26 tumors included, 57.7% were diagnosed as benign and 42.3% as malignant mesenchymal tumor. Cases diagnosed as benign mesenchymal tumor were hemangioma, lipoma, extra-abdominal fibromatosis, leiomyoma, angiofibroma, lipomatosis, benign fibrous histiocytoma and granular cell tumor. Histopathological study results were compatible with angiosarcoma in 5 (45.4%), undifferentiated sarcoma in 3 (27.3%), myxofibrosarcoma in 2 (18.2%) cases and rhabdomyosarcoma in 1 (9.1%) case.

CONCLUSION

Primary breast sarcomas are rarely seen compared to benign mesenchymal tumors and constitute less than 0.1% of all malignant breast tumors. When histomorphological findings suggestive of a mesenchymal tumor are observed in breast specimens, sufficient sampling should be performed to exclude a possible phyllodes tumor, and clinicoradiological findings should be examined to exclude the possibility of a metastasis.

Fibroepithelial Neoplasm with Hybrid Features of Benign Phyllodes Tumor, Juvenile Papillomatosis, and Juvenile Fibroadenoma: A Case Report

Phyllodes tumor is an uncommon breast fibroepithelial neoplasm mainly found in middle-aged patients, presenting a morphologic continuum from benign to malignant. Juvenile papillomatosis represents a rare benign proliferative breast tumor primarily affecting young individuals and carries a potential elevated risk of subsequent breast cancer development. Juvenile fibroadenoma is a well-circumscribed biphasic neoplasm that often occurs in adolescent girls, characterized by a pericanalicular growth pattern with usual-type epithelial hyperplasia and gynaecomastia-like micropapillary proliferation. Herein, we present an unusual example of a 26-year-old woman with a left breast outer lower quadrant palpable mass. Ultrasonography identified a 5.9 cm lobulated hypoechoic solid mass with scattered small cysts. The preoperative biopsy initially diagnosed a fibroepithelial lesion, considering giant cellular fibroadenoma and phyllodes tumor in the differential. Subsequent complete excision revealed areas of benign phyllodes tumor features closely admixed with distinctive elements such as prominent multiple cysts exhibiting apocrine and papillary apocrine metaplasia, duct papillomatosis, and duct stasis characteristic of juvenile papillomatosis, and hyperplastic ductal epithelium with micropapillary projections demonstrating a pericanalicular growth pattern indicative of juvenile fibroadenoma. The diagnosis was conclusively established as a fibroepithelial lesion with combined features of benign phyllodes tumor, juvenile papillomatosis, and juvenile fibroadenoma. Further investigation uncovered a family history of breast cancer. Molecular analysis revealed a pattern of unique and overlapping mutations within these distinct histopathological areas. This unusual presentation with hybrid features within a single tumor is described for the first time in the literature along with the molecular signature of the individual components.

microRNAs expression profile in phyllodes tumors of the breast

Proliferation of both stromal and epithelial components is a characteristic of fibroepithelial cancers of the breast. Certain fibroepithelial tumors of the breast, such as fibradenomas and phyllodes tumors, are challenging to distinguish and categorize. To find biomarkers for early diagnosis and improved disease management, it is crucial to deepen our understanding of the molecular pathogenesis pathways and tumor biology of PTs. It has been demonstrated that microRNAs (miRNAs) have significant roles in cancers; the expression pattern of miRNAs can help with cancer categorization and treatment. In contrast, little is understood about miRNAs in breast fibroepithelial cancers. This study was conducted retrospectively with the goal of assessing the expression of six mature miRNAs (hsa-miR-21, hsa-miR-155, hsa-miR-182, hsa-miR-34a, hsa-miR-148a, and hsa-miR-205) in breast fibroepithelial cancers using real-time PCR and predicting these miRNAs' targets using computational techniques. This study comprised 64 patients in total-55 with phyllodes tumors and 9 with fibroadenoma. The research was carried out at the Farhat Hached University Hospital's pathology department in Tunisia. These particular miRNAs expression levels were evaluated via qRT-PCR, and in silico techniques were utilized to predict potential miRNA targets. Analysis of miRNA expression in fibroadenoma and phyllodes tumor tissues revealed that miR-21, miR-155 and miR-182 were upregulated in PTs compared to fibroadenoma and normal tissues. We reported that miR-34a, miR-148a and miR-205 were downregulated in both borderline and malignant PTs compared to fibroadenoma and normal tissue. In silico miRNA target prediction suggested the involvement of these molecules in a wide context of cell signaling pathways.

Cystic squamous metaplasia in a giant benign phyllodes tumor of the breast: a case report

Phyllodes tumor is a rare tumor of the breast, which encompasses both stromal and epithelial components. In these components, metaplastic changes can be observed occasionally. We report the case of a 51-year-old woman nulligest menopaused who presented a huge mass, largely ulcerated in her right breast. The radiological examination revealed a large tumor with microcalcifications classified as Breast Imaging and Reporting Data System Category 5. The patient undergone right mastectomy and the histological analysis revealed benign phyllodes tumor with cystic squamous metaplasia. Therefore, we aim to present this uncommon event occasionally occurring in phyllodes tumor of the breast.

Machine Learning-Based Ultrasound Texture Analysis in Differentiation of Benign Phyllodes Tumors from Borderline-Malignant Phyllodes Tumors

PURPOSE

 Phyllodes tumors (PTs) are uncommon fibroepithelial breast lesions that are classified as three different forms as benign phyllodes tumor (BPT), borderline phyllodes tumor (BoPT), and malignant phyllodes tumor (MPT). Conventional radiologic methods make only a limited contribution to exact diagnosis, and texture analysis data increase the diagnostic performance. In this study, we aimed to evaluate the contribution of texture analysis of US images (TAUI) of PTs in order to discriminate between BPTs and BoPTs-MPTs.

METHODS

 The number of patients was 63 (41 BPTs, 12 BoPTs, and 10 MPTs). Patients were divided into two groups (Group 1-BPT, Group 2-BoPT/MPT). TAUI with LIFEx software was performed retrospectively. An independent machine learning approach, MATLAB R2020a (Math- Works, Natick, Massachusetts) was used with the dataset with p < 0.004. Two machine learning approaches were used to build prediction models for differentiating between Group 1 and Group 2. Receiver operating characteristics (ROC) curve analyses were performed to evaluate the diagnostic performance of statistically significant texture data between phyllodes subgroups.

RESULTS

 In TAUI, 10 statistically significant second order texture values were identified as significant factors capable of differentiating among the two groups (p < 0.05). Both of the models of our dataset make a diagnostic contribution to the discrimination between BopTs-MPTs and BPTs.

CONCLUSION

 In PTs, US is the main diagnostic method. Adding machine learning-based TAUI to conventional US findings can provide optimal diagnosis, thereby helping to choose the correct surgical method. Consequently, decreased local recurrence rates can be achieved.

Discrimination between phyllodes tumor and fibro-adenoma: Does artificial intelligence-aided mammograms have an impact?

Background

The indulgence of artificial intelligence (AI) has been considered recently in the work up for the detection and diagnosis of breast cancer through algorithms that could supply diagnosis as the radiologist do. The algorithm learns from a supervised and continuous input of large and new data sets unlike the standard programming, which requires clear step-by-step instructions. The aim of this study is to assess the ability of AI scanned mammograms to aid the ultrasound in the discrimination between phyllodes tumors and fibro-adenomas.

Results

This is a retrospective analysis included 374 proven phyllodes tumors (PT) and fibro-adenomas (FA). Digital mammogram and breast ultrasound was performed for all the cases and each breast was given a “Breast Imaging Reporting and Data System” (BI-RADS) score. Included mammograms were scanned by AI with resultant a qualitative heatmap and a quantitative abnormality scoring of suspicion percentage.

The study included 164 PT (43.9%) and 210 FA (56.1%). BI-RADS category 2 was assigned in 40.1%, category 3 in 38.2%, category 4 in 18.5% and category 5 in 3.2% with median value of the AI abnormality scoring of 23%, 44%, 65% and 90% respectively. Sensitivity and specificity of the conventional imaging were 59.2% and 75.8% respectively. The AI abnormality scoring of 49.5% upgraded the sensitivity to 89.6% and specificity to 94.8% in the ability to discriminate PT from FA masses.

Conclusion

Artificial intelligence-aided mammograms could be used as method of distinction between PT from FA detected on sono-mammogram. The color hue and the quantification of the abnormality scoring percentage could be used as a one setting method for specification and so guide clinicians in their decision of conservative management or the choice of the surgical procedure.

Malignant Phyllodes Tumor of the Breast: Case Report

Introduction: Phyllodes tumors (PT) are rare and account for 0.3% to 0.5% of all breast tumors. PT may be classified as benign, borderline or malignant. The aim of this study was to report a case of malignant PT of the breast. Case report: A 27-year-old woman presented with a mass in the left breast with histopathological features of malignancy (results of US of the breast: an oval, lobulated hypoechogenic lesion, measuring 7.7 cm – BI-RADS® 4C). A segmental resection (SR) of the breast was performed and histopathology study of the surgical specimen confirmed a malignant PT. Adjuvant radiotherapy was used for supplemental treatment. One year later, the patient had a local recurrence of the primary tumor and underwent a new SR of the left breast. There was no indication of breast reirradiation. At about 31 months after diagnosis (September 2019 – April 2022), the patient is well and adherent to periodical clinical follow-up. Conclusion: This study presents a case of malignant PT that occurred in a young patient and had a more aggressive course.

Merkel cell carcinoma of the breast: A case report

Merkel cell carcinoma (MCC) of the breast is a very rare and aggressive type of neuroendocrine carcinoma of the breast (NECB) that typically occurs in older and immunocompromised individuals often presenting as a large palpable mass (Albright et al., 2018¹). Imaging features of MCC are similar to other NECBs, typically appearing as an oval circumscribed mass on mammography and as an irregular mass with increased vascularity on sonography (Jeon et al., 2014²). While both MCC and primary NECB demonstrate positive immunostaining for synaptophysin, obtaining immunohistochemical stains for specific markers, such as CK7 and CK20 is imperative to confirm the diagnosis of MCC (Albright et al., 2018¹). We present a case of a 57-year-old female patient with no personal or family history of breast cancer, who presented for evaluation of a palpable abnormality in her left breast. Initial diagnostic mammogram demonstrated a circumscribed mass in the upper outer quadrant of the left breast corresponding to the palpable area of concern, which correlated to an irregular mass with increased vascularity on targeted ultrasound, similar to other NECBs. Pathologic results after tissue sampling yielded poorly differentiated primary NECB. Following neoadjuvant chemotherapy, the patient underwent a lumpectomy and further immunohistochemical stains of the lumpectomy specimen demonstrated diffusely positive synaptophysin, negative CK7, and positive CK20, consistent with MCC of the breast.

A Case of Phyllodes Tumor of the Breast with Mixed Liposarcoma: Case Report and Literature Review

Phyllodes tumors (PTs) account for less than 1% of breast tumors, and malignant PTs account for even less. Here, we described an unusual case of malignant PT with mixed liposarcoma (myxoid liposarcoma [MLP] and pleomorphic liposarcoma [PLP]). A 52-year-old woman discovered a small lump in her left breast. Twenty years later, the lump suddenly grew within 1 month. Mammography showed space-occupying lesions of the left breast. Histologically, the tumor was characterized by hypercellular stroma covering the epithelium and protrusion of the myoepithelium into the cyst to form a lobulated structure; regions of loose mucus and hypercellular structures alternated. A region of peripheral benign fibroadenoma was also observed, and many stellate and spindle cells or signet ring-like cells were identified in loose areas. Some areas showed a characteristic thin branching vascular pattern. In the cell-rich area, adipocytes and odd megakaryocytes were observed. Atypical mitotic figures were observed in the cell-rich and mucus areas (16 mitoses/10 high-power fields [HPF] and 2 mitoses/10 HPF, respectively). In the immunohistochemical analysis, a small number of tumor cells were positive for AE1/3 and vimentin, whereas all cells were negative for cytokeratin 34βE12, E-cadherin, p63, estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, and S-100, ruling out the possibility of metaplastic carcinoma. Interestingly, cyclin-dependent kinase 4, mouse double minute 2 (MDM2), and p16 were strongly positive in both loose mucus and cell-rich areas. However, the fluorescence in situ hybridization test results showed that MDM2 was not amplified. Combined with morphological characteristics, these findings supported that the tumor was a mixed malignant PT with MLP and PLP. Our patient did not receive radiation therapy, and after 47 months of follow-up, no recurrence or metastasis occurred. This case report serves to expand the morphologic spectrum of mixed malignant PT with liposarcoma.

Invasive ductal carcinoma arising in borderline phyllode tumor: A potential role of PIK3CA mutation

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Invasive carcinomatous lesions associated with borderline phyllodes tumors are extremely rare.

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Molecular biological mechanisms associated with this kind of lesions are unknown.

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PIK3CA gene mutation could be implicated in the development of these lesions.

Introduction

Carcinomatous lesions associated with phyllodes tumors are extremely rare and are found in less than 1% of all cases. To date, the molecular biological mechanisms associated with this carcinomatous transformation remain unknown.

Presentation of case

We present here the case of a 61-year-old patient with invasive ductal of no special type (NST) carcinoma originating in a borderline phyllode tumor with mutation in the PIK3CA gene.

Discussion

To the best of our knowledge, this mutation has never been described in this type of association.

Conclusion

Based on these data, we can better understand the ethiopathogenic molecular mechanisms in this type of lesion. Consequently, they could also in the future give rise to new therapeutic alternatives.

The implications of neighborhood socioeconomic status on surgical management and mortality in malignant phyllodes patients in the Surveillance, Epidemiology, and End Results program

BACKGROUND

Neighborhood socioeconomic status has been implicated in breast cancer incidence and mortality. However, there are no studies on the impact of neighborhood socioeconomic status on clinical outcomes or surgical management among patients with phyllodes tumors. The objective of this study is to understand the relationship between neighborhood socioeconomic status, surgical management and disease specific mortality in malignant phyllodes tumor patients in the Surveillance, Epidemiology, and End Results program.

METHODS

Surveillance, Epidemiology, and End Results program was queried for malignant phyllodes tumor patients diagnosed between 2000 and 2016. Using the National Cancer Institute census tract-level index for neighborhood socioeconomic status the data were stratified into low neighborhood socioeconomic status, middle neighborhood socioeconomic status, and high neighborhood socioeconomic status. Bivariate intergroup analysis was conducted. Disease specific mortality was evaluated using a Cox proportional hazards model.

RESULTS

Of the 651 patients with malignant phyllodes tumor in the sample, the disease specific mortality was 7.6% and 7.9% at 5 and 10 years, respectively. On bivariate analysis, there were no differences between the neighborhood socioeconomic status groups and surgery type (P = .794). On multivariable analysis, older age (≥71 years; hazard ratio 9.9; 95% confidence interval, 2.84-34.57; P < .001) and larger tumor size (≥40 mm; hazard ratio 2.20; 95% confidence interval, 1.09-4.44; P = .027) were associated with a higher disease specific mortality compared with younger age (≤ 40 years) and smaller tumor size (<40 mm). There was no association between neighborhood socioeconomic status and disease specific mortality (low neighborhood socioeconomic status-ref, middle neighborhood socioeconomic status hazard ratio 0.87 (95% confidence interval, 0.71-1.78; P = .71), high hazard ratio 0.91 (95% confidence interval, 0.44-1.90, P = .81).

CONCLUSION

Among malignant phyllodes tumor patients in the Surveillance, Epidemiology, and End Results program, disease specific mortality and surgical management are mostly driven by tumor characteristics and not social determinants of health.