Granulomatous hidradenitis suppurativa and cutaneous Crohn's disease.

Three patients with concurrent hidradenitis suppurativa and Crohn's disease are presented. The notable histological feature in each hidradenitis resection was the presence of numerous discrete epithelioid granulomas in areas of non-inflamed dermis. The purpose of the study was to determine the incidence of epithelioid granulomas in 101 hidradenitis patients and their significance in relation to systemic granulomatous disease. Discrete epithelioid granulomas were identified in 8% of the resections (10 patients). One patient had Crohn's disease and one other pulmonary sarcoidosis. Seven patients with granulomatous hidradenitis neither had nor developed any other disease during the 3-year follow-up period. Clinical review identified a further two patients with Crohn's disease but associated with non-granulomatous changes in the skin resections. Foreign body type granulomas were identified in 25% of the resections adjacent to ruptured hair follicles, sinus tracts or nearby degenerate sweat glands. The study shows that, although foreign body type granulomas are a common finding in hidradenitis, the presence of discrete epithelioid granulomas in the dermis away from the site of active inflammation is unusual and should alert the pathologist to the possibility of systemic granulomatous disease such as Crohn's disease or sarcoidosis.