Introduction:
Bullous pemphigoid (BP) is a bullous autoimmune skin disease that is characterized by autoantibodies targeting BP180 and BP230, which are two hemidesmosomal proteins localized at the epidermal-dermal junction [1]. BP is relatively common among elderly people, mainly affecting the trunk, lower limbs, and face [1]. Various drugs have been reported to show an association with BP [2]. Recently, there have been several reports that use of dipeptidyl peptidase-4 (DPP-4) inhibitors is associated with an increased risk of BP, with the highest risk being noted for vildagliptin among these drugs [3-6]. DPP-4 inhibitors are oral anti-diabetic drugs that inhibit degradation of incretins (gastric inhibitory peptide and glucagon-like inhibitory peptide -1). Several studies have shown that the clinical outcome is better if DPP-4 inhibitor therapy is discontinued when BP is diagnosed [7-9].
However, we experienced two cases of BP associated with DPP-4 inhibitor therapy showing unfavorable outcomes despite immediate discontinuation of the relevant drugs. Here, we report a total of three cases of DPP-4 inhibitor-associated BP in patients with type 2 diabetes, summarizing their characteristics and the clinical course of BP after discontinuation of DPP-4 inhibitors. Patients provided informed consent for publication of these cases.