Metaplastic carcinomas of the breast—fine needle aspiration (FNA) cytology findings

Abstract

Metaplastic carcinomas of the breast are defined by mesenchymal and/or squamous cell components associated with ductal carcinoma and may raise diagnostic problems in FNA cytology. We reviewed FNA smears of a series of nine cases; seven were compared with histological sections and two with cell-block sections. The cytological pattern was diagnostic of carcinoma in six cases; in two cases a diagnosis of sarcoma/phyllodes tumour was considered, as cells were predominantly spindle-shaped. One case had a pleomorphic adenoma type pattern. The cytological findings suggesting a diagnosis of metaplastic carcinoma include a liquid aspirate, a proteinaceous or chondromyxoid background and a poorly differentiated tumour with multinucleated giant cells, neoplastic or histiocytic. A definite diagnosis requires the presence of both carcinomatous and metaplastic (squamous/mesenchymal) components.

Metaplastic Carcinoma of the Breast: Cytological Diagnosis and Diagnostic Pitfalls

“…Because of the rarity of metaplastic breast carcinomas, a relatively small number of studies are available regarding the clinical and pathological features of this neoplasm [2,16,21]. Moreover, only 4 large case series have described the cytological features of metaplastic carcinomas, with the other published studies mainly being case reports [9,12,24,25,26]. Since in developing countries, fine needle aspiration is the first diagnostic modality for diagnosing breast cancer, reporting of cytological features of this entity is imperative.…”

“…More importantly even, in the 11 biphasic tumors, dual components were identified on cytology in only 5 cases [12]. In another study by Nogueira et al [25], fine needle aspirates were diagnostic of carcinoma in 6/9 reviewed cases. A diagnosis of sarcoma/phyllodes was considered in 2 cases because of the predominance of spindle cells, and the other case was confused with pleomorphic adenoma.…”

Fine Needle Aspiration Cytology of Fibroadenoma with Multinucleated Stromal Giant Cells

“…15 They often represent sarcomatous transformation of carcinoma cells and show a certain degree of nuclear pleomorphism. A definitive diagnosis of metaplastic carcinoma requires the identification of carcinomatous and mesenchymal components.…”

Indeterminate and Erroneous Fine-Needle Aspirates of Breast with Focus on the ‘True Gray Zone': A Review

“…While primary breast sarcomas are exceedingly rare, malignant PTs with stromal overgrowth and metaplastic spindle-cell carcinoma represent the most common malignant spindle-cell lesions of the breast. The presence of a conspicuous, benign (albeit proliferative), epithelial component would favor a PT, while a biphasic epithelial/mesenchymal phenotype or the presence of malignant squamous differentiation would favor a MC [118,119,120]. When dealing with a purely sarcomatoid proliferation, the distinction between PT, MC or primary mammary sarcoma becomes immaterial as all three neoplasms mandate wide surgical excision without the need for axillary lymph node dissection in the absence of a clinically positive axilla [121].…”