Henoch–Schönlein purpura induced by sitagliptin: A case report

Dipeptidyl peptidase-4 inhibitors are oral antihyperglycemic medications often used as adjuncts to other antidiabetic agents to treat type 2 diabetes mellitus. Henoch–Schönlein purpura, also known as ImmunoglobulinA (IgA) vasculitis, is a form of IgA-mediated leukocytoclastic vasculitis, which is rarely reported in adults. Herein, we report the case of a 52-year-old male with type 2 diabetes mellitus who presented with petechiae, ecchymoses, and palpable purpura below the knees bilaterally after starting sitagliptin, a dipeptidyl peptidase-4 inhibitor. A punch biopsy for direct immunofluorescence showed granular Immunoglobulin A, M, and complement 3 in vessel walls, suggestive of Henoch–Schönlein purpura. Sitagliptin was discontinued, and the patient was treated with celecoxib, colchicine, and cefadroxil for wound infection. Three months after initial presentation, brown hyperpigmentation was appreciated, suggestive of post-inflammatory changes and resolution of the lesions. However, urinalysis revealed new 0.3 g/L protein. Overall, this case highlights a new potential association of dipeptidyl peptidase-4 inhibitors with Henoch–Schönlein purpura, which may have systemic consequences.