Metastatic intracavitary cardiac aortic body tumor in a dog

A mobile right-ventricular mass dynamically occluding the right ostium atri oventriculare in the systolic phase was detected in a 3-year-old male Tosa dog by echocardiography. At necropsy, multiple tumor masses of various size s were observed in the heart base, right ventricular lumen, myocardium, lun g and liver. Dysplasia of tricuspid valve characterized by irregular shape of leaflets, upward malposition of large papillary muscles, and shortened a nd stout chordae tendineae was also detected. Histopathologically, the tumo r cells, arranged in sheets or nests, were polyhedral with lightly eosinoph ilic and finely granular cytoplasm, and contained a hyperchromatic round or oval nucleus. By Grimelius' silver stain, tumor cells had cytoplasmic posi tive granules. Ultrastructurally, tumor cells contained characteristic smal l membrane-limited granules. This is the first report of metastatic intraca vitary cardiac aortic body tumor in a dog.