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

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.