When Immunotherapy Breathes Trouble: Rituximab-induced Lung Injury in a Case of Relapsing Demyelination

Rituximab, a potent B-cell-depleting agent widely used for autoimmune and demyelinating disorders, can rarely cause serious pulmonary toxicity.We report a 24-year-old woman with relapsing demyelinating disease who developed progressive, unexplained dyspnea shortly after initiating rituximab.She had no prior cardiopulmonary illness and had previously received high-dose methylprednisolone and intravenous immunoglobulin (IVIG).Initial evaluation, including chest radiography and echocardiography, was unremarkable.After two infusions, given 15 days apart, she developed worsening breathlessness without fever or evidence of infection.Subsequent imaging revealed findings suggestive of drug-induced lung injury.Extensive investigations excluded infectious, cardiac, and autoimmune causes, and a temporal association established the diagnosis of rituximab-induced lung injury (RILI).Rituximab was discontinued, and systemic corticosteroids were started, resulting in marked clinical improvement.This case highlights the need for high clinical suspicion for RILI in patients with new respiratory symptoms following rituximab, as early recognition and prompt treatment are critical to prevent significant morbidity.