Answer: Epithelioid angiomyolipoma

Histology: This is a neoplasm composed of eosinophilic cells, which in the liver naturally suggests a hepatocellular neoplasm. However, the cells have a somewhat spider like cytoplasm, in that there is focal clearing with tentacles of eosinophilic cytoplasm radiating to the periphery of the cell. The lesion lacks the typical sinusoidal vascular pattern of a hepatocellular lesion. On immunohistochemistry, the lesion was negative for HEPAR-1, but did label for HMB45, typical of angiomyolipoma/PEComa.

Discussion: Hepatocellular carcinoma would feature more sinusoidal vascular pattern, and typical arises in the setting of cirrhosis. Hepatocellular carcinomas would not label for HMB45 and typically do label for HEPAR-1. Hepatocellular adenomas also would label for HEPAR-1 but not for HMB45. Focal nodular hyperplasia would have a morphology more typical of cirrhosis, in that it features hepatocyte nodules separated by proliferating bile ducts and fibrosis, but forms a focal lesion. Another name for focal nodular hyperplasia is “focal cirrhosis”.