Experience With Janus Kinase Inhibitors in Acquired Perforating Dermatosis in Older Adults: A Case Series and Review of Literature

Acquired perforating dermatosis (APD) is a group of conditions characterized by transepidermal elimination and extrusion of dermal components. Patients often present with severe pruritus to the degree of disordering daily life and have comorbid diabetes mellitus (DM) or chronic kidney disease (CKD). However, owing to the limited number of cases, unmet clinical needs exist for effective treatment in the absence of large‐scale clinical trials and established clinical guidelines. Therefore, this study aimed to broaden the scope of current APD treatment by investigating the role of Janus kinase (JAK) inhibitors through five case series, thereby adding to the two previously reported cases of APD treated with JAK inhibitors. Patients reported improvement in pruritus as early as 1 day with JAK inhibitor treatment, and this improvement was mainly observed within the first 4 weeks. Improvement in the hyperkeratotic nodule with central plug lesions was also observed. One patient developed herpes zoster reactivation during the course. The reduction of pruritus may be critical in disease management, both as a prominent symptom and a precipitating factor of APD. As the JAK–STAT pathway is suggested to play a critical role in IL‐31 signal transduction, a key cytokine in itching, JAK inhibitors may be an effective treatment for difficult‐to‐treat APD. Vigilant monitoring for adverse events, such as infection, with patient education is also warranted.