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.

The transformation of a benign phyllodes tumor (PT) into a malignant PT and/or carcinoma is extremely uncommon. We present a case of a 66-year-old female with a huge mass on the left breast which was successfully removed by surgical resection. The pathological diagnosis was infiltrating lobular carcinoma with pure rhabdoid features and the malignant transformation of a benign phyllodes tumor. The first time this rare case was reported, it is demonstrated a special phenomenon through the synchronous transformation of PT grades and the carcinomatous transformation of PT.

BACKGROUND: Optimal surgical margin width for patients with phyllodes tumors (PTs) of the breast remains debated. The aim of this study was to assess the influence of margin width on long-term local recurrence risk.
METHODS: This was a single-institution retrospective review of patients with confirmed PT treated from 2008-2015. Margins were defined as positive (ink on tumor), narrow (no tumor at inked margin but < 10mm), or widely free (>/= 10mm). LR rates were estimated by the Kaplan-Meier method.
RESULTS: Among 117 female patients, histology included 55 (47%) benign, 29 (25%) borderline, and 33 (28%) malignant PT. Final margins were positive in 16 (14%), narrow in 32 (27%), widely free in 64 (55%), and unknown in 5 (4%) patients. Compared with margins > 10 mm, patients with positive and narrow margins had a higher LR risk [HR 10.57 (95% CI 2.48-45.02) and HR 5.66 (95% CI 1.19-26.99), respectively]. Among benign PTs, the 10-year LR-free rates were 100%, 94%, and 66% for widely negative, narrow, and positive margins, respectively (p = 0.056). For borderline/malignant PT, the 10-year LR-free rates were 93% and 57% for widely negative and narrow margins, respectively (p = 0.02), with no difference in LR between narrow and positive margin groups (p = 1.00).
CONCLUSIONS: For benign PTs, a margin of no ink on tumor appears sufficient to optimize local control. In patients with borderline or malignant PTs, achieving a wide surgical margin may remain important as narrower margins were associated with LR rates comparable to those with positive margins.

Breast phyllodes tumor (PT) is a rare fibroepithelial neoplasm with potential malignant behavior. Long non-coding RNAs (lncRNAs) play multifaceted roles in various cancers, but their involvement in breast PT remains largely unexplored. In this study, microarray was leveraged for the first time to investigate the role of lncRNA in PT. We identified lncRNA ZFPM2-AS1 was significantly upregulated in malignant PT, and its overexpression endowed PT with high tumor grade and adverse prognosis. Furthermore, we elucidated that ZFPM2-AS1 promotes the proliferation, migration, and invasion of malignant PT in vitro. Targeting ZFPM2-AS1 through nanomaterial-mediated siRNA delivery in patient-derived xenograft (PDX) model could effectively inhibit tumor progression in vivo. Mechanistically, our findings showed that ZFPM2-AS1 is competitively bound to CDC42, inhibiting ACK1 and STAT1 activation, thereby launching the transcription of TNFRSF19. In conclusion, our study provides evidence that ZFPM2-AS1 plays a pivotal role in the pathogenesis of breast PT, and suggests that ZFPM2-AS1 could serve as a prognostic indicator for patients with PT as well as a promising novel therapeutic target.

UNASSIGNED: 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.

Phyllodes tumors (PTs) of the breast are rare fibroepithelial neoplasms, typically characterized by their benign nature. We present a unique case of a 29-year-old Pakistani female who initially presented with a benign PT in her left breast. Despite undergoing multiple surgical resections over the course of a decade, the tumor exhibited a remarkable transformation in biology, progressing from a benign phenotype to malignancy. Subsequent recurrences manifested with increasing aggressiveness, ultimately culminating in distant metastasis to the bones, axillary nodes, chest wall, and abdominal wall. This case underscores the unpredictable nature of PTs and highlights the challenges in managing recurrent cases with malignant transformation. The clinical course described herein emphasizes the importance of vigilant monitoring and individualized treatment strategies in such cases.

UNASSIGNED: Breast phyllodes tumors (BPT) have variable malignant potential, their histological classification remains insufficient for an accurate diagnosis.
UNASSIGNED: We attempted to investigate CD10 (Cluster of differentiation 10) and EGFR (Epidermal growth factor receptor) expression in BPT in order to highlight their diagnostic and prognostic values.
UNASSIGNED: Eight patients with BPT are recruited from January 2014 to December 2020 and immunohistochemical assessment of CD10 and EGFR is realized.
UNASSIGNED: Median age was 27±15.2, the mean tumor size was 9.63±10.21. Only malignant tumours showed expression for EGFR. Borderline and malignant tumors were CD10 positive. Patients overexpressing CD10 were postmenopausal with great tumor size, 25% of these were sarcomatous. Coexistence of CD10 and EGFR overexpression was found in 25% of cases and was associated with age (P=0.008), tumor size (P=0.030) and hitologic types (P=0.014). PC1 and PC2, were extracted, they accounted cumulatively for 94.7% of the variance of the data analysed, it suggests that patient\'s age and histological type of tumor have significant association with CD10 and EGFR expression in BPT.
UNASSIGNED: EGFR and CD10 overexpressed combined proteins in phyllode tumors constitute, with histopathological parameters, an important prognostic factor as well as a promising potential targets.

Phyllodes tumor is an uncommon breast neoplasm that is present in variable sizes. Giant phyllodes are those larger than 10 cm in diameter. Clinically, giant phyllodes tumors present as a visible, rapidly growing mass distorting the breast contour. Such tumors with large size and rapid growth rate suggest a phyllode diagnosis of fibroadenoma. Planning a standard treatment strategy for these tumors is quite challenging. While adequate surgical excision with tumor-free resection margins is the standard of care for most giant phyllodes cases, borderline and malignant giant phyllodes tumors might require wider resections given their high recurrence rates. Some authors described total mastectomy as the treatment option for giant borderline and malignant phyllodes to obtain wide, clear margins. Between March 2022 and September 2023, our surgical oncology department presented and operated on three cases of giant phyllodes. They underwent a nipple-sparing mastectomy and immediate breast reconstruction using pre-pectoral silicone implants. We think that with such a procedure, we can benefit from the wide, safe margins of mastectomy that have been proven to decrease local recurrence rates while considering the aesthetic outcome.

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.

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.