Unusual radiologic manifestation of pseudoprogression in pulmonary metastases after durvalumab treatment in metastatic bladder urothelial cancer

Durvalumab is an immune checkpoint inhibitor that blocks PD‐L1. Unlike cytotoxic chemotherapy or molecularly targeted agents, immune checkpoint inhibitors occasionally present distinct response patterns, including radiologic pseudoprogression (initial tumor enlargement with subsequent tumor regression) and immune‐related adverse events in normal tissues. We report a case of unusual computed tomography (CT) findings of pseudoprogression of pulmonary metastases in a patient with metastatic bladder cancer after durvalumab treatment: multiple pulmonary metastases turned into ground‐glass opacity on first follow‐up CT; on second follow‐up CT, and after sustained treatment of the PD‐L1 inhibitor, the lesion was resolved.