Hepatocellular carcinoma (HCC) is an aggressive cancer associated with high mortality worldwide. HCC develops in the setting of underlying cirrhosis due to chronic liver disease. Surgery is usually considered the treatment of choice for early disease; however, most patients have locally advanced or metastatic HCC at diagnosis in which case treatments are limited. Immune checkpoint blockade of programmed death receptor-1 (PD-1) pathway offers a potential treatment strategy based on the encouraging results of the phase I/II trial of nivolumab (Checkmate 040 trial). This has led to the off-label use of nivolumab after failure of treatment with sorafenib either due to intolerance or progression of disease. Although rare (<5%), clinical response to anti-PD-1 antibody may be preceded by "pseudoprogression" -- increase in the size and number of tumor lesions before actual tumor shrinkage. We report a case of pseudoprogression followed by an excellent response in an HCC patient treated with nivolumab and review the literature for ongoing trials of immune checkpoint blockade in HCC. The pseudoprogression in our case is supported by increase in both tumor size and alpha-fetoprotein after four treatments with nivolumab; however, regression of tumor size and normalization of alpha-fetoprotein occurred after subsequent treatments. To our knowledge, there are no reports of pseudoprogression in HCC although pseudoprogression has been well described in melanoma
