Clinical Study of Bullous Pemphigoid With Oral Mucosal Symptoms After Oral Administration of Dipeptidyl Peptidase‐4 Inhibitors

ABSTRACT Dipeptidyl peptidase‐4 (DPP‐4) inhibitors are widely used for diabetes treatment. However, reports of DPP‐4 inhibitor‐associated bullous pemphigoid (BP) have been increasing. This study examined 12 cases of BP with oral mucosal lesions associated with DPP‐4 inhibitor therapy. Six cases presented with only oral mucosal lesions, while the other six patients had non‐inflammatory skin lesions. Discontinuation of DPP‐4 inhibitors led to symptom improvement in nine cases, whereas three cases did not improve, with lesion progression to the pharynx. Remission was achieved after a mean of 20.8 ± 24.6 months after DPP‐4 inhibitor discontinuation, but two cases relapsed. Anti‐BP180 NC16a antibodies were positive in six cases, while full‐length BP180 ELISA was positive in 8 of 10 tested cases. These findings suggested that DPP‐4 inhibitor‐associated BP frequently involves oral mucosal lesions, and some cases may present solely with mucosal symptoms. Given the potential for recurrence and severe progression, long‐term follow‐up is essential.