Cutaneous necrotic lesion: A wonderful delay adverse effect of interferon beta-1b injection for multiple sclerosis treatment.

Multiple sclerosis (MS) is a chronic and inflammatory autoimmune disease. These patients may manifest severe inflammatory cutaneous reactions after using interferon beta-1b. This article describes a 55-year-old man with severe injection site reactions after 10 years administration of interferon beta-1b. The biopsy specimens revealed skin and subcutaneous tissue necrosis. Histologic evaluation revealed nonspecific inflammatory reactions with no evidence of vasculitis or granulomatous reactions. Based on clinical and pathological findings, the diagnosis of skin and soft tissue necrosis due to interferon injection was given. The injection of interferon beta-1b in the affected areas was stopped, and the patient's clinical condition improved by wound care. This report is aimed to increase awareness about severe adverse skin reactions, which may infrequently occur with subcutaneous interferon beta-1b injection after several years. Early diagnosis of this reaction can help to prevent associated complications.