Unique clinical and serological features of bullous pemphigoid associated with dipeptidyl peptidase‐4 inhibitors

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Funding sources: this study was supported by Grants‐in‐Aid for Research on Measures for Intractable Diseases from the Ministry of Health, Labour, Welfare and the Keio Gijuku Academic Development Fund.

Conflicts of interest: none to declare.

Dear Editor, Recently, several cases of bullous pemphigoid (BP) associated with the use of a dipeptidyl peptidase‐4 (DPP‐4) inhibitor, a type of antihyperglycaemic drug, have been reported (DPP4i‐BP).1,2 Béné et al. reported a strong association between DPP‐4 inhibitor use and the risk of BP.3 The juxtamembranous extracellular noncollagenous 16a (NC16a) domain of type XVII collagen (also termed BP180) is a major target epitope of autoantibodies in BP.4 A recent study found that in individuals with BP, whose autoantibodies bound to BP180 at regions other than NC16a, exhibited a noninflammatory phenotype with fewer erythemas. Intriguingly, half of these patients had taken DPP‐4 inhibitors at the time of development of BP.5 In this study, we explored whether individuals with DPP4i‐BP exhibited any unique clinical and serological features as suggested by the previous study.