Cutaneous Manifestations of ANCA-Associated Small Vessels Vasculitis Angelo Valerio Marzano 1 & Maria Gabriella Raimondo 2 & Emilio Berti 1 & Pier Luigi Meroni 2,3 & Francesca Ingegnoli 2 Published online: 3 June 2017 # Springer Science+Business Media New York 2017 Abstract Skin lesions are frequent manifestations of under- lying systemic conditions, including systemic autoimmune vasculitis. In particular, anti-neutrophil cytoplasmic antibod- ies (ANCA) are associated with distinct forms of vasculitis characterized by inflammatory cell infiltration of the walls of small and medium-sized vessels leading to vascular destruc- tion and tissue necrosis. ANCA-associated vasculitis is rare and systemic diseases, which can be classified based on different distribution of vascular inflammation and presence or absence of granulomatosis and asthma. Despite their di- versities, ANCA-associated vasculitis, namely microscopic polyangiitis, granulomatosis with polyangiitis and eosino- philic granulomatosis with polyangiitis, can all display a broad variety of cutaneous manifestations, which can appear during the course of the disease or even as first sign at the time of onset. Different skin manifestations might coexist in the same patient and occur in different occasions during the course of the vasculitis. Thus, a deep knowledge of the spectrum of skin lesions as part of ANCA-associated vascu- litis is mandatory for a correct diagnostic process, whenever cutaneous vasculitis is suspected. Due to this broad variety of manifestations, the diagnosis of skin involvement in ANCA-associated vasculitis is very challenging and it must be supported by a detailed medical history, accurate physical examination, specific histopathological analysis of skin bi- opsy and the presence of ANCA serology. In this review, we focus on the cutaneous manifestations that can develop in the context of ANCA-associated vasculitis, detailing the clinical features, the histopathological aspects as well as the direct immunofluorescence studies for each of the three conditions. Moreover, we acknowledged the differential di- agnoses that must be ruled out in the diagnostic process and the main therapeutic approaches available for treatment of ANCA-associated vasculitis. Keywords Anti-neutrophil cytoplasmic antibodies . Vasculitis . Skin . Granulomatosis with polyangiitis . Eosinophilic granulomatosis with polyangiitis . Microscopic polyangiitis Abbreviations ANCA Anti-neutrophil cytoplasmic antibodies AAV ANCA-associated vasculitis PR3 Leukocyte proteinase 3 GPA Granulomatosis with polyangiitis MPO Myeloperoxidase MPA Microscopic polyangiitis EGPA Eosinophilic granulomatosis with polyangiitis ENT Ear, nose and throat CSVV Cutaneous small vessel vasculitis PG Pyoderma gangrenosum PAN Polyarteritis nodosa Prof. Marzano and Dr. Raimondo equally contributed to this article. * Pier Luigi Meroni pierluigi.meroni@unimi.it 1 Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Unità Operativa di Dermatologia, IRCCS Ca’ Granda, Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy 2 Division of Rheumatology, ASST Pini, Department of Clinical Sciences and Community Health, Università degli Studi di Milano, Milan, Italy 3 Experimental Laboratory of Immunological and Rheumatologic Researches, IRCCS Istituto Auxologico Italiano, Cusano Milanino, Milan, Italy Clinic Rev Allerg Immunol (2017) 53:428–438 DOI 10.1007/s12016-017-8616-5