Ustekinumab-induced Henoch-Schönlein purpura in Crohn’s disease: a case report and literature review

Crohn's disease is a chronic inflammatory disease of the digestive tract with extraintestinal manifestations, which include skin conditions, arthritis, ocular inflammation, and several autoimmune conditions. Dermatologic manifestations in Crohn's disease complicate the treatment course and prognosis and should be addressed promptly. Here, we report a 20-year-old male with a history of Crohn's disease, presenting with palpable purpura, consistent with Henoch-Schönlein purpura, upon administration of ustekinumab. The immunoglobulin A vasculitis was treated with prednisone and the discontinuation of ustekinumab. Due to the increased usage of biological agents in inflammatory bowel diseases, associations between biologics and vasculitides should be further studied in Crohn's disease patients for alternative treatment strategies and to understand potential adverse effects caused by biologics in Crohn's disease.