Sitagliptin-associated Bullous Pemphigoid Complicated by Secondary Candidiasis, Urosepsis, and Gastrointestinal Bleeding in an Elderly Diabetic Woman.

Bullous pemphigoid (BP) is the most common autoimmune blistering disease in older adults and is increasingly associated with dipeptidyl peptidase-4 (DPP-4) inhibitors used in type 2 diabetes mellitus. Sitagliptin-associated BP is uncommon and may be complicated by secondary infections and multisystem involvement. A 74-year-old female with type 2 diabetes mellitus and hypertension presented with generalized weakness, burning micturition, abdominal pain, painful blistering skin lesions, and oral erosions. She had been receiving sitagliptin 100 mg once daily for approximately 2 years before symptom onset. Skin biopsy demonstrated a subepidermal bulla with eosinophilic infiltrates, suggestive of BP. Sitagliptin was discontinued after admission. The hospital course was complicated by bilateral pyelonephritis with multidrug-resistant urosepsis requiring bilateral double-J stenting, oral candidiasis caused by Candida albicans, recurrent gastrointestinal bleeding, and tubulovillous adenoma with high-grade dysplasia. Persistent dermatologic disease with markedly elevated immunoglobulin E levels necessitated omalizumab therapy, resulting in gradual improvement. Sitagliptin-associated BP should be considered in elderly diabetic patients presenting with blistering disorders after prolonged gliptin exposure. Early diagnosis, withdrawal of the suspected drug, histopathological confirmation, and multidisciplinary management are essential for favorable outcomes.