A rare case of unresectable, microsatellite instability-high hepatocellular carcinoma and an examination of the tumor microenvironment.

Hepatocellular carcinoma (HCC) is a common cause of cancer-related deaths worldwide, and the mortality rate of patients with unresectable HCC is very high. Microsatellite instability (MSI) is an essential biomarker for response to immune checkpoint inhibitors (ICI) in various tumors. However, the frequency of MSI in HCC is low (1.