A case of primary clear cell hepatocellular carcinoma in a non-cirrhotic liver: an immunohistochemical and ultrastructural study.

The clear cell variant of hepatocellular carcinoma is a rare entity, occurring at a frequency of less than 10% of hepatocellular carcinoma, with a female prevalence and usually associated with hepatitis C and cirrhosis. We reported a case of primary clear cell hepatocellular carcinoma occurring in a non-cirrhotic liver without history of hepatitis. Our examination included gross pathology, histopathology, immunohistochemistry, special stains, and electron microscopy evaluation. The tumor was composed of sheets of medium-to-large cells with foamy and reticulated cytoplasm and small-to-medium sized nuclei with variably prominent nucleoli. Oil red O stain showed abundant intracellular lipid. Periodic Acid-Schiff stain confirmed the presence of abundant glycogen deposition. Immunohistochemically the tumor cells were positive for Hep Par1, negative for epithelial membrane antigen, steroidogenic factor-1, HMB45, melan A, CK7 and CK20. Electron microscopy study was performed, which was first done in a clear cell hepatocellular carcinoma occurring in a non-cirrhotic liver without elevation of liver function tests. Ultrastructural evaluation of the clear cells showed scarce cellular organelles, cytoplasmic lipid vacuoles and swollen mitochondria.