Benzylthiouracil-induced ANCA-associated Vasculitis: A Case Report and Literature Review

Iatrogenic antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) is not exceptional. Many cases of small vessel vasculitis induced by anti-thyroid drugs (ATD), mainly propylthiouracil (PTU), have been reported. We present a case of AAV related to another ATD: benzylthiouracil (BTU) and review the literature. An 84-year-old man with a 4-year history of multinodular goitre with hyperthyroidism was treated with BTU. He presented an acute syndrome with weakness, fever, epigastric pain and abdominal distension. Lactate and lipase tests were normal. An abdominal scan showed a thrombosis of the splenic artery with splenic infarction. We excluded a hypothesis of associated embolic aetiology: atrial fibrillation, atrial myxoma, intraventricular thrombus or artery aneurysm. Exploration of a possible prothrombotic state (complete blood count, haemostasis tests, activated protein C resistance, factor V Leiden, protein C, S, antithrombin III) gave normal results. Tests for antinuclear antibodies (ANA) and antiphospholipid antibodies (APL) were negative. However, testing for p-ANCA, with antimyeloperoxidase (MPO) specificity, was positive: 120.6 CU (N