Ectopic hidradenoma papilliferum: A case report and review of the literature

Hidradenoma papilliferum is a benign, cystic, papillary tumor that occurs a lmost exclusively in women on the skin of the anogenital region. Nonanogeni tal (ectopic) hidradenoma papilliferum are rare. We describe a 72-year-old white man with an enlarging nodule in the region of the right triceps muscl e; microscopic examination showed a hidradenoma papilliferum. The median ag e of patients with ectopic hidradenoma papilliferum is between 1 to 2 decad es older than the average age range of lesion onset in patients with anogen ital hidradenoma papilliferum. In contrast to anogenital hidradenoma papill iferum, nearly one half of the patients with ectopic hidradenoma papillifer um are men. Ectopic hidradenoma papilliferum occurs most frequently (60%) i n the head and neck region. Eighty-five percent of cases are 1.5 cm in the greatest diameter or smaller. The race, clinical features, pathologic featu res, treatment, and prognosis for hidradenoma papilliferum occurring in ano genital and ectopic locations are similar.