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.