Rhabdomyosarcoma with FocaI Cartilaginous Differentiation (Malignant Mesenchymoma) of the Inferior Vena Cava

Abstract
A sarcoma arising from the inferior vena cava occupied the entire lumen of the inferior vena cava, right atrium, hepatic veins and conmon iliac veins. Its histological appearance was non‐ specific sarcoma, except for the presence of a few rhabdomyoblasts and some immature cartilaginous tissue. lmmunohistochemically, some tumor cells were positive for myoglobin, desmin, HHF‐35, and vimentin. Electron microscopy revealed that some tumor cells contained myofilaments and Z bands in the cytoplasm, which are characteristics of rhabdomyosarcoma. The tumor was diagnosed as rhabdomyosarcoma with focal cartilaginous differentiation (malignant mesenchymoma) of the inferior vena cava. Acta Pathol Jpn 42: 382–385, 1992.