Clinical characteristics, genetics, comorbidities and treatment of palmoplantar pustulosis: A retrospective analysis of 66 cases in a single center in Taiwan.

We retrospectively analyzed 66 patients with palmoplantar pustulosis (PPP) from January 1994 to September 2019 in our department. Interleukin-36 receptor antagonist gene (IL36RN) intron 3 c.115+6T>C mutation was present in two out of 27 patients (7.4%). Both cases developed generalized pustular psoriasis and/or acrodermatitis continua of Hallopeau later. Topical medications and phototherapy were used in 93.9% and 28.8% of patients, respectively, while 60.6% received systemic agents. The majority of patients (60.6%) responded to treatment, but episodes of flare-up existed. The demographic data of our patients with PPP showed female predominance (59.1%), middle-age onset (44.2 years old) and current smokers (62.1%). Generalized pustular psoriasis initially presenting as palmoplantar lesions may be misdiagnosed as PPP, and the presence of IL36RN mutation may serve to predict or confirm the diagnosis of future generalized pustular psoriasis or acrodermatitis continua of Hallopeau. To our knowledge, this is the largest demographic study of PPP in Taiwan.