Ocrelizumab-induced organizing pneumonia in multiple sclerosis: case report and literature review

Patients with relapsing-remitting multiple sclerosis should be offered disease-modifying therapies as part of their management. Recommended options include integrin antagonist therapy including natalizumab as well as anti-CD20 monoclonal antibodies like, ocrelizumab, rituximab, ofatumumab, and ublituximab. These therapies reduce relapse rates and slow brain lesion accumulation. Disease-modifying therapies selection may depend on patient preferences, potential fetal harm, and specific drug risks, requiring continuous monitoring via tracking clinical relapses and new MRI brain lesions. Natalizumab carries a risk of progressive multifocal leukoencephalopathy, particularly in anti-JCV antibody-positive patients, necessitating regular monitoring. Ocrelizumab, rituximab, and ublituximab are associated with an increased risk of infections (especially respiratory and skin infections), infusion reactions, and hypogammaglobulinemia. Ocrelizumab additionally poses a heightened risk of immune-mediated colitis and breast cancer, and it is contraindicated for patients with active hepatitis B due to the risk of viral reactivation. Ublituximab has been noted to be linked to potential fetal harm. We report the case of a 42-year-old male with relapsing-remitting multiple sclerosis on ocrelizumab who developed persistent fever and shortness of breath, two weeks after his last ocrelizumab dose. Despite antibiotic treatment for suspected pneumonia, his symptoms persisted. A chest CT scan revealed multifocal ground-glass opacities suggestive of organizing pneumonia, likely secondary to ocrelizumab. The patient's condition improved with high-dose corticosteroids, underscoring the importance of vigilance for extremely rare ocrelizumab-associated pulmonary side effects and the need for prompt, appropriate intervention.