Low-grade fibromatosis-like spindle cell metaplastic carcinoma: a basal-like tumor with a favorable clinical outcome. Report of two cases.

Fibromatosis-like spindle-cell metaplastic carcinoma (FLSpCC) is an atypical variant of spindle-cell carcinoma with a particular clinical behavior characterized by frequent local recurrence, very low potential for axillary lymph node metastasis, and uncommon distant metastases. Although it presents the typical immunoprofile of basal-like carcinomas, FLSpCC is associated with a favorable clinical outcome and conservative treatment is generally indicated. Because of the lack of specific clinical and radiological characteristics, the criteria for the differential diagnosis from other benign and malignant tumors are based only on histological findings and immunostaining. We report on two FLSpCC patients treated with wide local excision and mastectomy associated with axillary lymph node dissection. Although the biological behavior of this subtype of breast cancer has not been adequately evaluated, wide local excision or mastectomy with clear resection margins but no axillary dissection appears to be an adequate treatment approach.