Rituximab-Induced Serum Sickness in Patients With Multiple Sclerosis: A Case Report and Literature Review

Rituximab is a chimeric anti-CD20 monoclonal antibody that is becoming increasingly used in multiple sclerosis. In rare cases, rituximab may induce a delayed immune-mediated reaction such as rituximab-induced serum sickness. We report the case of a 49-year-old woman with multiple sclerosis who developed rituximab-induced serum sickness characterized by fever, diffuse rash, lymphadenopathy, and arthralgia nine days after her first rituximab infusion. We reviewed the number of cases in a literature review, discussing their characteristics and mechanisms and the implications for using alternative anti-CD20 monoclonal antibodies such as ocrelizumab or ofatumumab for the management of multiple sclerosis.