Abstract
We report the case of a 73-year-old female patient with malignant melanoma who developed rapidly progressive dermatosclerosis of the arms and legs as well as myalgia and flexion contractures during treatment with the immune checkpoint inhibitor nivolumab. The diagnosis of a myofasciitis was confirmed by imaging and biopsy. Following consultation with the treating dermato-oncologists nivolumab treatment was paused and treatment with methotrexate and prednisolone was initiated. Immune checkpoint inhibitors can induce a variety of immune-mediated side effects and can also imitate symptoms of rheumatological diseases. The occurrence of myofasciitis under immune checkpoint inhibition has been reported in the literature only in a few cases. Further oncological and rheumatological treatment management should be carried out in close interdisciplinary coordination.