An uncommon perianal nodule: hidradenoma papilliferum.

Hidradenoma papilliferum is a rare, benign, cystic, papillary apocrine gland tumor that occurs almost exclusively in women in the skin of the anogenital region. We present the case of a 66 year old woman who presented with a progressively enlarging perianal nodule. We provide a review of the literature emphasizing the clinico-pathological characteristics and differential diagnosis. Local excision is necessary for identification and cure. No recurrence was observed after one year follow-up.