A malignant and metastasizing feline cardiac ganglioneuroma.

In the current study, a case of a cardiac ganglioneuroma with systemic metastases in a cat is described. A 12-year-old male neutered Japanese domestic cat was brought to a veterinary hospital for dysorexia, coughing, vomiting, and diarrhea. Ultrasonography revealed a mass adjacent to the right atrium. The animal died of respiratory failure 1 month after the first visit to the hospital. At necropsy, an oval-shaped white mass 1.5 cm in diameter was observed within the right auricle. Diffusely, the right ventricle was infiltrated and thickened by the neoplastic lesion. Histologically, the mass was composed of 3 types of neoplastic cells: spindle cells, large polygonal cells, and small undifferentiated cells. Immunohistochemically, the neoplasia was positive for neuronal markers such as βIII tubulin, S-100a, and protein gene product 9.5. Ultrastructurally, the large polygonal cells were characterized by abundant cytoplasm that included compressed Golgi cisternae and rough endoplasmic reticula and abundant intermediate filaments. A discontinuous basement membrane surrounded the spindle cells. Metastatic foci were found in the lungs, kidney, pancreas, urinary bladder, and adrenal glands. The morphological, immunohistochemical, and ultrastructural characteristics of the tumor cells were consistent with those of ganglioneuroma. The tumor was presumed to originate from the intramural parasympathetic ganglia in the right atrium.