Alemtuzumab-induced lung injury in multiple sclerosis: Learning from adversity in three patients

•We report three cases of severe lung injury in MS patients treated with alemtuzumab.•Lung injury was heterogeneous in terms of clinic characteristics, HRCT pattern and onset timing.•All cases were reversible after steroid therapy, but re-treatment is challenging. Respiratory alemtuzumab-related adverse events are clinically heterogeneous and include respiratory infections, infusion-related dyspnea, hypoxia and secondary autoimmune disorders. Here we report three cases of drug-induced lung disease following treatment with alemtuzumab in multiple sclerosis patients. First case was diagnosed as a non-specified intestitial pneumonitis associated with organizing pneumonia with subacute onset, second case was an acute respiratory distress syndrome with onset during second cycle, third case was a diffuse acute alveolar hemorrhage during first cycle infusion. All patients developed acute respiratory failure, reversible after steroid therapy. Clinicians should be aware to early recognize acute and subacute respiratory adverse events for a promptly management. In these patients re-treatment is challenging.