[Bilateral carpal tunnel syndrome in a patient with malignant melanoma undergoing adjuvant pembrolizumab therapy].

Immune checkpoint inhibitors (ICIs) are successfully used in multiple malignant diseases. Their spectrum of adverse effects includes dermatological, endocrinological, gastrointestinal, and hepatic toxicities, as well as rare neurological side effects affecting the central nervous system and more frequently the peripheral nervous system. Pre-existing neurological disorders may deteriorate. Bilateral carpal tunnel syndrome (CTS) rarely occurs. In the present case, an 83-year-old patient with stage IIIC malignant melanoma (MM) developed pain, swelling, and paresthesia in both hands after five adjuvant therapy cycles with pembrolizumab 200 mg. Following the diagnosis of bilateral CTS, pulse therapy with prednisolone was initiated and subsequently reduced to a maintenance dose of 20 mg orally. Despite the necessary escalation of ICI therapy to ipilimumab/nivolumab due to MM progression, CTS improved under concomitant prednisolone therapy and physiotherapy.