Coincidental occurrence of hepatocellular carcinoma and cholangiocarcinoma (collision tumors) after liver transplantation: a case report.

Coincidental occurrence of hepatocellular carcinoma (HCC) and cholangiocarcinoma, known as "collision tumors", within a cirrhotic liver is rare. Herein, we report a case of liver transplantation (LT) in a patient with such collision tumors. Our patient was a 56-year-old woman with hepatitis C virus-related cirrhosis and 2 focal hepatic lesions, measuring 1.5 and 3 cm, in the liver segments 8 and 5, respectively. The lesion on segment 8 showed the typical radiological characteristics of HCC; however, the lesion in segment 5 showed an atypical vascular pattern and was closely associated with the inferior vena cava. Serum alpha-fetoprotein level was normal and serum carbohydrate antigen 19-9 (CA19-9) level was slightly elevated (63 U/mL); the extrahepatic spread of HCC was ruled out. The patient underwent an uneventful deceased-donor LT. Histopathological examination of the explant confirmed that the lesion on segment 8 was an HCC, but surprisingly, the lesion on segment 5 was found to be a cholangiocarcinoma. Six months after LT, the serum CA19-9 level was markedly elevated (255 U/mL), and the patient began experiencing abdominal pain. Magnetic resonance imaging showed enlarged hilar and paraaortic lymph nodes that were suggestive of metastases; histopathological analysis using ultrasound (US)-guided biopsy confirmed recurrent cholangiocarcinoma. Unfortunately, the patient died because of tumor recurrence 9 months after LT.Collision tumor resulting from the co-existence HCC and cholangiocarcinoma in a cirrhotic liver is rare and has a negative impact on the outcome of LT. Atypical vascular pattern and elevated serum CA19-9 levels are suggestive of such tumors; patients with these findings should undergo a targeted biopsy to rule out the coincidental occurrence of HCC and cholangiocarcinoma.