Rituximab induced sympathetic crashing acute pulmonary oedema in a patient with interstitial lung disease: a rare and lifethreatening complication

Rituximab is a monoclonal antibody widely used to treat autoimmune diseases and haematologic malignancies. Although generally well tolerated, it can cause severe infusion-related reactions, including pulmonary complications. Sympathetic crashing acute pulmonary oedema (SCAPE) is a rare but potentially life-threatening manifestation of autonomic deregulation, characterised by sudden hypertensive crisis, pulmonary congestion and respiratory distress. We report a case of a 77- year-old Sri Lankan man with Interstitial lung disease (ILD), radiologically consistent with a usual interstitial pneumonia (UIP) pattern, likely associated with rheumatoid arthritis. He did not respond adequately to mycophenolate mofetil (MMF) and was switched to Rituximab. Four hours after infusion, he developed acute respiratory distress, hypertension and pulmonary oedema. Immediate management with intravenous glyceryl trinitrate (GTN), furosemide infusion and continuous positive airway pressure (CPAP) ventilation led to rapid symptom resolution, preventing invasive ventilation. Rituximab-induced pulmonary oedema is a rare but critical complication, likely mediated by excessive sympathetic activation, cytokine release and haemodynamic shifts. Patients with preexisting ILD may be at higher risk due to reduced pulmonary reserve. This case underscores the need for clinical vigilance during rituximab infusion in a patient with ILD and highlights the importance of early recognition and intervention.