A case of herpetiform pemphigus mimicking bullous pemphigoid after using secukinumab and successfully treated with sulfasalazine

Abstract Interleukin 17A (IL‐17A) inhibitors, such as secukinumab, have been widely used as the mainstream treatment for chronic plaque psoriasis; however, cutaneous adverse events have been reported. Here, we report a 43‐year‐old Chinese man who developed herpetiform pemphigus (HP) during secukinumab treatment for his psoriasis. He presented with (1) clinical features of HP, which resembled bullous pemphigoid; histopathological features of intraepidermal blisters, eosinophilic/neutrophilic spongiosis, and liquefactive degeneration of the basal cell layer; (3) positive anti‐desmoglein 1 antibody by enzyme‐linked immunosorbent assay and cell surface IgG reactivity within the epidermis by indirect immunofluorescence assay; and (4) a satisfactory response to salicylazosulfapyridine (sulfasalazine). To the best of our knowledge, this is the first report of the development of HP after the use of secukinumab for psoriasis.