18F-FDG PET/CT in a Patient With Matrix-Producing Carcinoma of the Breast.

A 47-year-old woman presented with a large mass in the upper inner quadrant of the left breast. 18F-FDG PET/CT revealed a low-density left breast mass with heterogeneous ring-like 18F-FDG uptake. Core needle biopsy of the tumor revealed a rare subtype of metaplastic breast carcinoma, matrix-producing carcinoma. The tumor size slightly decreased after 6 cycles of neoadjuvant chemotherapy with docetaxel and epirubicin. The left breast was entirely resected subsequently, and the matrix-producing carcinoma of the breast was ultimately diagnosed.