MON-522 Sitagliptin Induced Bullous Pemphigoid-A Rare But Devious Side Effect

Abstract Disclosure: S. Atreya: None. K. Yagnik: None. J. Pava Delos Rios: None. N. Patel: None. Background: Sitagliptin is a commonly used medication which is used to treat diabetes mellitus type 2 by inhibiting the enzyme dipeptidyl peptidase-4 (DPP-4). Here in, we present an uncommon case of sitagliptin associated bullous pemphigoid (BP). Case presentation: A 75 year old male came with pruritic, fluid filled blisters primarily on his feet, left more than right. He has significant past medical history of diabetes mellitus type 2 for 30 years, asthma, hypertension and hyperlipidemia. Blisters were heralded with a prodrome of generalised itching and were gradually worsening over a period of 6-8 months. Initially, the etiology of blisters was thought to be infectious, however, a short course of doxycycline didn’t show any improvement. Over the period of time, blisters extended over his arms, back and chest, but spared the face and mucosal membranes. He started on methylprednisolone initially, later switched to oral prednisone. Sitagliptin was discontinued. A biopsy from the right arm revealed pathology suggestive of bullous pemphigoid. The patient was discharged on steroid taper and topical triamcinolone resulted in full resolution of the bullae in 2 weeks. Discussion: Immunobullous disorders, most commonly bullous pemphigoid, is being recorded as a commonly emerging side effect of DPP-4 inhibitors. Although the onset of drug-induced BP typically occurs within months of medication initiation, delayed presentations even after decades are being increasingly recognized. This case reinforces the need to maintain clinical suspicion for medication-induced BP, even in long-term users of DPP-4 inhibitors. Prompt withdrawal of the offending agent, along with immunosuppressive therapy, most commonly steroids, can result in swift clinical response. Therefore a high suspicion is a prerequisite for rapid diagnosis and prompt discontinuation of the offending agent for best outcomes. Presentation: Monday, July 14, 2025