Metaplastic breast carcinoma with chondrosarcomatous differentiation: fine-needle aspiration cytology findings. A case report.

Metaplastic carcinoma (carcinoma with pseudosarcomatous metaplasia) of the breast are high-grade carcinomas in which much of the tumor undergoes metaplastic change producing a pseudosarcomatous pattern. We report a case of metaplastic breast carcinoma (MBC) in whom fine-needle aspiration (FNA) cytology was performed with later histological confirmation. The lesion affected a 68-yr-old woman, with a tumor measuring 6.4 x 5.3 cm well demarcated mass located in the upper outer quadrant of the right breast. FNA cytology revealed a variety of markedly atypical cells, mainly spindle-shaped, and mitotic figures sporadically distributed against a severely necrotic background. Atypical chondrocytes were observed against a background of myxomatous substance that displayed metachromasia with May-Giemsa stain that resembled chondrosarcoma cells. Clusters of markedly atypical carcinoma cells that exhibited epithelial junctions were also seen, and immunostaining confirmed the presence of both mesenchyme-marker-positive sarcomatous and epithelial-marker-positive carcinoma cells. Careful attention to the precise cellular composition such as sarcomatous cells, chondrosarcomatous cells and carcinoma cells should allow the recognition of these neoplasms. Therefore, MBC seems to be very a characteristic tumor in which accurate cellular diagnosis may be achieved by FNA cytology. (C) 2006 Wiley-Liss, Inc.