Chronic hidradenitis suppurativa of the anal canal. A surgical skin disease.

Obstruction of the outlet of the apocrine duct adjacent to the skin surface, with subsequent rupture into the intradermal plane, initiates the inflammatory condition termed "hidradenitis suppurativa." The chronic manifestations of the process, indicated by recurrent abscess formation, draining sinuses, skin fistulas, and an intense cicatricial response, usually affect the distal two thirds of the anatomic anal canal because the proximal portion is devoid of hair follicles and accessory glands. An anal fistula that lacks continuity with the cryptoglandular units of the dentate margin or intersphincteric space (or both) is suggestive of the presence of hidradenitis. The fistula of chronic hidradenitis suppurativa can be diagnosed by a track that originates in a pitlike scar, usually epithelialized, within the skin of the distal anal canal, which then progresses beyond the anal verge superficial to the internal sphincter muscle. A group of 30 patients have been followed up from one to seven years and are without evidence of recurrent symptoms in the anal canal.