Fine-needle aspiration of a metaplastic breast carcinoma with extensive melanocytic differentiation: A case report

Metaplastic carcinomas of the breast are uncommon tumors with aberrant cell ular differentiation, most commonly showing ductal, squamous, and mesenchym al components. A breast carcinoma composed of both epithelial and melanocyt ic differentiation is rare, with only four previously reported cases in the literature. We present the fifth reported case, where the diagnosis was su ggested by fine-needle aspiration (FNA) and later confirmed after the surgi cal specimen was excised. Histologically, this neoplasm revealed multidirec tional differentiation, consisting primarily of squamous and melanocytic ce ll types, with focal glandular and osseous metaplasia. Based on the morphol ogic, immunohistochemical, and ultrastructural findings, we conclude that s uch tumors fall within the spectrum of metaplastic carcinomas of the brest. We believe that this case will further contribute to the understanding of this enigmatic tumor. (C) 2000 Wiley-Liss, Inc.