Immunotherapy causing pneumonitis in a patient with non-small cell lung cancer (NSCLC).

Our patient, who had been previously diagnosed with non-small cell lung cancer, presented with progressive dyspnoea after receiving second-line immunotherapy treatment with atezolizumab. Chest CT scan showed bilateral lung architectural distortion, bronchial dilatation, consolidative opacities, ground-glass opacities and linear opacities concerning for either infectious lung disease or treatment-related lung disease. A diagnostic bronchoscopy was performed and no evidence of malignancy or infection was detected. Discontinuing atezolizumab with the addition of oral corticosteroid improved the patient's respiratory symptoms but the patient required continuous oxygen supplementation. Later, the patient was found to have radiologic findings suggestive of further progression of his pneumonitis after completion of a course of corticosteroid treatment and required another course of oral prednisone. Immune-mediated pneumonitis could present with mild to severe respiratory symptoms with a wide range of clinical and radiologic features and physicians should be aware of this diagnosis of exclusion. Although patients may experience progressive disease with or without immunotherapy rechallenge, most of these cases can be managed successfully with favourable outcomes.