Rare "Inverted" Verrucous Carcinoma (Carcinoma Cuniculatum) of the Sacrogluteal Region: Case Report and Literature Review.

A 49-year-old woman with a past history of several infundibular cysts in the head and neck region presented with a 6-month history of a nonhealing perianal abscess on a background of 13 years of chronic sacral-buttock abscesses and discharging sinuses as part of hidradenitis suppurativa. After 2 surgical procedures and inadequate healing, a wide local excision was performed. The surgical specimen revealed an extensive, infiltrating, cystic and deeply penetrating, dermal and subcutaneous neoplasm with multiple fistulous tracts extending to the skin surface. The histopathology was consistent with carcinoma cuniculatum, a rare, slow growing, verucciform variant of squamous cell carcinoma. An entirely subcutaneous verrucous carcinoma of the sacrogluteal region is exceptionally rare, and this represents the first documentation of such a case in a female.