Hidradenitis suppurativa and vasculitis: A case series and literature review of a rare association.

Hidradenitis suppurativa is a chronic inflammatory skin disease with dysregulation of the immune system. Its pathophysiology is not clear, and it has been reported in association with various inflammatory disorders such as pyoderma gangrenosum, arthritis, familial Mediterranean fever and inflammatory bowel diseases. However, the co-existence of HS and vasculitis is exceptional and has not been investigated. We report on five patients with vasculitis that are followed in our centers: one with Takayasu's arteritis, three with granulomatosis with polyangiitis and one with Behcet's disease and compare them with those previously reported in the literature. A case series and literature review with key words of "vasculitis," "hidradenitis suppurativa," and "acne inversa" found only one previous report of hidradenitis suppurativa and cutaneous vasculitis and two with Behcet's disease. Whereas the association of pyoderma gangrenosum and vasculitis is well-known, that with hidradenitis suppurativa is rarer. There may be some pathogenic continuum between hidradenitis suppurativa, pyoderma gangrenosum and vasculitis.