Cytomegalovirus hepatitis after treatment with dostarlimab for colorectal cancer

A man in his early 40s was receiving treatment for rectal cancer with dostarlimab, an immune checkpoint inhibitor (ICI), when he developed fevers, headache and nausea. He was hospitalised with elevated liver enzymes and infectious work-up revealed an acute cytomegalovirus (CMV) infection. With concern that his dostarlimab therapy could be contributing to his inflammatory response as an ICI-induced hepatitis, the patient underwent a liver biopsy. Pathology was instead consistent with CMV hepatitis, and the patient was treated with antiviral therapy and had complete resolution of his illness. This case illustrates the importance of monitoring for immune-related adverse effects in patients taking ICIs, while still maintaining a broad differential diagnosis for other causes.