Hepatic leiomyosarcoma: ultrastructural study and review of the differential diagnosis.

A primary leiomyosarcoma of the liver in a 12 year old female is reported. It is the eleventh such tumor to be recorded, the first to be documented in an adolescent and the first to be studied electron microscopically. By light microscopy the well differentiated portions of the tumor were characteristic of leiomyosarcoma. Ultrastructurally a minority of tumor cells contained myofilaments along with cytoplasmic dense bodies and marginal dense plaques, the most distinctive subcellular markers of smooth muscle cells. A brief review of the differential diagnosis is provided.