[Annular leukocytoclastic vasculitis: A particular form of small vessel vasculitis?]

Leukocytoclastic vasculitis is characterized by necrotizing inflammation around small blood vessels, composed mainly of neutrophils. Skin lesions in leukocytoclastic vasculitis are polymorphous, but a rare annular variant exists of which dermatologists must be aware. Herein we present a new case of this entity.

We report the case of a 74-year-old man who developed annular purpuric infiltrated lesions mainly on the lower limbs, with leukocytoclastic vasculitis being confirmed by histology. This annular leukocytoclastic vasculitis regressed spontaneously with no recurrence after 6 months. The aetiology was not established.

Annular leukocytoclastic vasculitis is rare, and the mechanisms underlying annularity and peripheral spread as well as the aetiology remain unexplained. This form of vasculitis with unusual clinical features may constitute a new entity in the subclass of immune complex small vessel vasculitis within the Chapel Hill classification. While the aetiology and physiopathology of this vasculitis are unknown, despite the possibility of recurrence, skin involvement appears isolated and the condition carries a good prognosis.