Breast carcinoma with tumor giant cells. Report of a case with fine needle aspiration cytology.

A 31-year-old woman presented with a cystic mass in the left breast. At fine needle aspiration (FNA), the mass felt gritty, and a firm mass remained after drainage of the cyst. Cytologic examination of the aspirate showed mononucleated malignant cells and an array of bizarre malignant multinucleated giant cells. A diagnosis of carcinoma of breast with malignant giant cells was made. Subsequent histologic study of the lesion showed a central cystic cavity lined by bizarre tumor giant cells. Immunocytochemistry and lectin cytochemistry confirmed the epithelial nature of the malignant giant cells. The entities that may yield giant cells on FNA of breast masses are discussed.