Cutaneous manifestations of ANCA‐associated vasculitis: a retrospective review of 211 cases with emphasis on clinicopathologic correlation and ANCA status

Abstract Background ANCA‐associated vasculitis (AAV) may present a wide array of dermatological manifestations. Patients may remain ANCA negative, rendering diagnosis challenging for dermatologists if they depend heavily on ANCA testing to either confirm or rule out AAV. Objective To compare clinical and histopathological features of AAV patients with skin lesions who are ANCA positive versus those who are ANCA negative. Methods Retrospective review of medical charts to identify patients diagnosed with AAV by clinical and pathologic criteria who also had cutaneous manifestations. Results Search revealed that 211 out of 932 (23%) patients had cutaneous manifestations. Of those, 40/211 (20%) patients had persistently ANCA‐negative serology. Eosinophilic granulomatosis with polyangiitis (EGPA) comprised the largest cohort. Palpable purpura was the most prominent clinical feature. The most common histopathological feature was leukocytoclastic vasculitis (LCV) in 19 (29%) specimens, extravascular granuloma in 14 (22%), followed by perivascular infiltrate in 12 (18%), with eosinophils in nine. In the ANCA‐negative subgroup, perivascular infiltrate was more common followed by LCV but without statistically significant difference. Conclusions Diagnosis of AAV should not be based on ANCA testing alone since a considerable number of patients with cutaneous lesions may be ANCA negative. The clinical or histopathologic findings of skin lesions in this study group did not vary based on ANCA status.