Interferon beta-1a–induced morphea

IL-4: Interleukin 4 IFN-b: Interferon beta IFN-b1a: Interferon beta-1a MS: Multiple sclerosis SSc: Systemic sclerosis Th2: T helper 2 INTRODUCTION Interferon beta-1a (IFN-b1a) is a cytokine therapy used in the treatment of relapsing-remitting multiple sclerosis. The most common adverse injection site reactions include local erythema, pain, and induration. Other less frequently encountered reactions include vascular thrombosis, ulceration, panniculitis, and lipoatrophy. More recently, IFN-b rarely has been noted to be associated with sclerosing skin disorders including limited and diffuse systemic sclerosis; however, the development of morphea has not been reported. Here we describe a patient with multiple sclerosis who had woody induration clinically and histologically consistent with morphea at the sites of subcutaneous IFN-b1a injections.