Abstract

Both hidradenitis suppurativa (HS) and cutaneous Crohn disease (CCD) exhibit ulcerations (including knife-like ulcers), fissures, sinus tracts, and edema. Correct diagnosis may rely on histopathologic distinction. However, comparative histopathologic data are lacking, overlapping microscopic features may be observed, and some patients with intestinal Crohn disease may have both CCD and HS. Despite the considerable overlap, response to treatment and clinical course differ in patients with both diseases.

In both HS and CCD, granulomas and plasma cells are identified. The granulomas of HS are most commonly foreign body-type granulomas due to follicle or cyst rupture, while the granulomas of CCD are epithelioid type with Langhans giant cells. Another clue is the location of the granulomas within the inflammation, as the granulomas of CCD are often distant to the  inflammation and ulceration. These concepts are illustrated by two patients with both HS and CCD.  In case 1, a 16-year-old girl with a history of HS of the axillae and groin presented with a new knife-like fissure in the gluteal crease and a superimposed skin tag; histopathology demonstrated epithelioid granulomas distant to ulceration, reflecting CCD. In case 2, a 26-year-old woman presented with multiple knife-like ulcers of the groin and axillae, along with nodules cysts and scarring in the same distribution; an excisional specimen demonstrated both foreign body-type granulomas of HS and epithelioid granulomas of CD. Therefore, biopsy and histopathological distinction should be attempted when review of systems and physical examination lead to high clinical suspicion of CCD.