Primary rhabdomyosarcoma of the adult liver.

A 53-year-old male Caucasian presented with a massive liver tumor composed entirely of spindle-shaped cells showing light-microscopic and ultrastructural evidence of rhabdomyoblastic differentiation. No epithelial or other sarcomatous elements were included. Detailed postmortem examination failed to reveal evidence of metastatic tumor or an alternative primary site. There have been only four previous cases of primary rhabdomyosarcoma of the adult liver, all occurring in Japanese men.