Mucin-producing hepatocellular carcinoma without morphological features of biliary differentiation: A case report

RATIONALE: Hepatocellular carcinoma has been believed not to produce mucin unless it has biliary differentiation. However, some cases of hepatocellular carcinoma with extracellular myxoid change have been reported recently, raising the possibility that, in rare cases, hepatocellular carcinoma cells produce mucin. PATIENT CONCERNS: Here we report a case of hepatocellular carcinoma that contained intracellular and extracellular myxoid matrix without morphological evidence of biliary differentiation, although cells in a portion of the tumor were positive for the epithelial markers cytokeratin 7 and 19. She was brought to our hospital due to abnormal liver tests and a large liver tumor found by ultrasound examination. DIAGNOSES: The liver tumor showed typical imaging findings of hepatocellular carcinoma. INTERVENTIONS: The tumor was resected with negative margins, and pathologically diagnosed as hepatocellular carcinoma with mucin production. OUTCOMES: The patient has been free from recurrence of cancer during two-years’ follow-up. LESSONS: Our case suggests that hepatocellular carcinoma cells can produce mucin without or before morphological differentiation to biliary phenotypes, an observation that may help elucidate the mechanism for the development of combined hepatocellular and cholangiocarcinoma.