Fine needle aspiration cytology of granulomatous mastitis. Report of a case and review of the literature.

A case of granulomatous mastitis diagnosed by fine needle aspiration (FNA) cytology alone is reported. A 24-year-old pregnant woman presented with a six-week history of a rapidly enlarging breast mass, considered clinically to be malignant. The FNA smears contained numerous aggregates of epithelioid histiocytes admixed with Langhans' and foreign-body giant cells, lymphocytes, neutrophilic leukocytes and apoptotic debris, leading to a diagnosis of granulomatous mastitis. The features of granulomatous mastitis and its differential diagnoses are discussed.