Gingival-Dominant Presentation of DPP-4 Inhibitor-Associated Bullous Pemphigoid: A Case Report

Bullous pemphigoid (BP) is an autoimmune subepidermal blistering disease that predominantly affects elderly individuals and has recently been associated with dipeptidyl peptidase-4 (DPP-4) inhibitor therapy. Oral involvement is uncommon, and gingival-dominant presentations are particularly rare. We report a case of DPP-4 inhibitor-associated BP presenting primarily with gingival lesions in a 76-year-old woman with type 2 diabetes mellitus treated with teneligliptin. The patient initially presented with persistent gingival white lesions and erosions, followed by the subsequent development of cutaneous bullae. Serological testing revealed elevated anti-BP180 antibody levels. Histological analysis of a skin biopsy demonstrated subepidermal blister formation with eosinophilic infiltration, and direct immunofluorescence showed linear deposition of C3, IgG, and IgA along the basement membrane zone. Teneligliptin was discontinued and treatment with topical corticosteroids, oral nicotinamide, and tetracycline-class antibiotics resulted in gradual resolution of both oral and cutaneous lesions without prolonged systemic corticosteroid therapy. Anti-BP180 antibody levels decreased in parallel with clinical improvement during long-term follow-up. This case highlights the diagnostic challenges of gingival-dominant BP and emphasizes the importance of considering DPP-4 inhibitor-associated BP in elderly patients with refractory gingival lesions, as well as the value of interdisciplinary collaboration between dentistry and dermatology.