HISTOCHEMICAL AND ULTRASTRUCTURAL CHARACTERIZATION OF PRIMARY CARDIACCHONDROSARCOMA

A cardiac chondrosarcoma was found in the right atrium of a Golden Ret riever dog. Macroscopically, the right atrial lumen was filled with a 6- X 12- X 8-mm white glossy mass, which was diffusely attached to the underling myocardium. The mass was composed of spindle-shaped mesench ymal neoplastic cells loosely packed in light basophilic matrix, with focal areas of tightly packed cells in linear formation similar to the pattern of a growth plate. Tumor cells were positive when stained for vimentin and neuron-specific enolase, and weakly positive for S-100 p rotein. Ultrastructurally, neoplastic cells had abundant, dilated roug h endoplasmic reticulum, Golgi apparatus, bundles of intermediate fibe rs, and primitive intercellular junctions between adjacent tumor cells . Based on morphologic, ultrastructural, histochemical, and immunohist ochemical characteristics, this tumor was diagnosed as a chondrosarcom a.