Metaplastic Carcinoma of the Breast

The following two cases illustrate part of the histology spectrum of metaplastic carcinoma of the breast. Both are predominantly spindle cell lesions, with immunohistuchemical evidence of epithelial differentiation. They differ in histologic grade, and this difference is reflected in the clinical behavior of these lesions. A case of spindle cell metaplastic tumor with dominant fihromatosis-like phenotype that recurred locally, and a case of spindle cell metaplastic carcinoma with a dominant low intermedinte-grade fibrosarcoma componene that metastasized to the hung, are presented. A review of the pertinent literature, including recent data on low-grade spindle cell metaplastic tumors, is provided.