Hepatocellular carcinoma in a transplanted donor liver and colon cancer developing in a patient with a complex background: A case report

The development of tumors in livers transplanted from hepatitis B virus (HBV)‑negative donors to patients with hepatitis B and cirrhosis is rare. The present study describes the case of a woman in her 60s who developed hepatocel‑ lular carcinoma (HCC) in her grafted liver, 19 years after transplantation, as well as a metachronous colorectal tumor. The pathological findings, including clinical, immunohisto‑ chemical and molecular results, are described in the present case report. The liver tumor was a conventional HCC and the colorectal tumor comprised a tubular adenocarcinoma. Immunohistochemistry of both tumors showed a loss of expression of mutL homolog 1 and postmeiotic segregation increased 2 in the tumor cells, confirming microsatellite instability‑high (MSI‑H) status. Furthermore, a molecular study detected the presence of genes located on the Y chromo‑ some in the normal and tumor tissues of the liver, proving that the HCC occurred in the grafted liver. The present report also discusses that prolonged use of immunosuppressive drugs to prevent post‑transplant rejection, poorly controlled diabetes mellitus and MSI‑H may have contributed to the risk of tumor development.