Uncommon presentations in ANCA vasculitis: clinical characteristics and outcomes.

ANCA-associated vasculitis (AAV) can present in an atypical manner and obscure the clinical picture. We sought to characterize clinical characteristics and outcomes in these uncommon presentations. We conducted a retrospective study of 171 AAV patients in our vasculitis database to identify patients with atypical presentation of AAV. Patient demographics, serologies, renal indices, and treatment regimens were assessed. Of the 171 patients, eight were identified to have uncommon presentations. These patients were usually extremes of age with three being less than 30 years and four being more than 70 years. Six patients were positive for PR3 antibodies. The mean delay in diagnosis from time of symptom development was 12 months. All patients developed acute kidney injury during their clinical course. Pancreatitis was the most frequent atypical presentation (n = 3), with pulmonary pathologies (cystic lung disease and usual interstitial pneumonia) and splenic infarcts being present in two patients each. The diagnosis of AAV was established by positive ANCA serology and renal or lung biopsy evidence of vasculitis. Six patients received induction therapy with steroids and rituximab, while two received steroids and cyclophosphamide. One patient died of respiratory failure in the first month following diagnosis while the remaining patients achieved disease remission. One patient developed end-stage renal disease. Uncommon presentations of AAV afflict extremes of age with a PR3 ANCA predominance and are associated with subsequent development of AKI. This case series demonstrates that a significant delay in diagnosis can be associated with these presentations. KEY POINTS: • Uncommon manifestations of AAV are seen more often with PR3 ANCA disease and respond to standard induction therapy of AAV. • High index of suspicion is required to avoid delays in diagnosis.