Association of hidradenitis suppurativa with Crohn's disease.

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disorder characterized by recurrent nodules, abscesses, and sinus tracts. Crohn's disease (CD) is characterized by inflammation of the entire digestive tract and belongs to the group of inflammatory bowel diseases, and there are many extraintestinal manifestations, among which hidradenitis suppurativa is one of the rare extraintestinal manifestations. There appears to be a strong association between CD and HS based on clinical and histological similarities (sinus tract development, granulomatous inflammation, and scarring), intersections in pathogenesis (genetic loci, immune dysregulation mechanisms, and microbiome changes), and commonality in treatment. In this review, we summarize recent studies on the association between HS and CD.