Cutaneous vasculitidis: histology and immunofluorescence

Cutaneous vasculitis comprises a wide spectrum of diseases that involve predominantly the blood vessels and surrounding tissues of the skin. Few vasculitic syndromes have pathognomonic clinical, radiographic and/or laboratory findings; thus, confident and accurate diagnosis of vasculitis requires histological confirmation. Skin biopsy should be done, optimally within 24 to 48 hours after vasculitic lesions appear. Deep excision biopsy must be preferred. Direct immunofluorescence of lesional skin is helpful in the diagnosis of vasculitides in the light of a proper clinico-pathological setting and diagnostic in some peculiarly forms. Cutaneous histological patterns can be used to generate relevant clinical differential diagnoses, and, when coupled with patient's history, clinical and laboratory data, allow more precise and accurate diagnosis of vasculitic syndromes. This review will focus on histopathological and immunologic pattern of the more common cutaneous vasculitis syndromes, based on the 2012 Revised International CHCC.