Secondary Organising Pneumonia Among Immunocompromised Multiple Sclerosis Patients Treated With Ocrelizumab Following COVID-19 Infection: Two Case Reports With Literature Review.

Publication date: Jul 01, 2025

Anti-CD20 medications, such as rituximab and coronavirus disease 2019 (COVID-19) infection, have been shown to cause secondary organising pneumonia (OP). Ocrelizumab is an anti-CD20 monoclonal antibody widely used as a disease-modifying therapy for relapsing-remitting and primary progressive forms of multiple sclerosis (MS). We describe two cases of biopsy-proven secondary OP in ocrelizumab-treated MS patients occurring several weeks after contracting COVID-19 infection. These cases had been on ocrelizumab for 6. 5 years (latent period) before the development of OP. Withdrawal of ocrelizumab and corticosteroids resulted in clinical and radiographic recovery. Literature review revealed seven cases of secondary OP in ocrelizumab-treated MS patients without evidence of infection and 10 MS cases with secondary OP due to COVID-19 infection in the setting of ocrelizumab treatment. Although unproven, ocrelizumab could trigger pneumotoxicity in patients when combined with COVID infection.

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