Cytologic atypia in a 53-year-old man with finasteride-induced gynecomastia.

Finasteride has been associated with the development of gynecomastia. Although cytoplasmic vacuolization has been noted in prostatic epithelium in men taking this drug, we found no documentation of the cytologic changes in finasteride-associated gynecomastia. We present the case of a 53-year-old man who developed unilateral gynecomastia following finasteride therapy for alopecia. A fine-needle aspiration biopsy of the mass was diagnosed as adenocarcinoma on the basis of nuclear atypia and particularly because of cytoplasmic vacuolization. Subsequent excisional biopsy revealed benign gynecomastia with no evidence of malignant change. The ductal epithelium did exhibit cytoplasmic vacuolization similar to that described in the prostate following finasteride therapy. We believe this is the first reported case documenting the cytologic changes seen in gynecomastia secondary to finasteride therapy. Cytoplasmic vacuolization in this setting should not be considered evidence of malignancy in men with gynecomastia. As with gynecomastia in general, extreme caution should be used before rendering a cytologic diagnosis of malignancy.