Ganglioneuromatosis of the Gallbladder in a Dog with Cholecystitis and Cholestasis.

A 2-year-old entire female mixed-breed dog was presented with signs of cholestasis. Abdominal ultrasonography revealed a gallbladder with a thickened and hyperechoic wall and luminal calculi. Exploratory laparotomy with cholecystectomy was performed and histopathological examination of the specimens from the cholecystectomy demonstrated extensive proliferation of large, prominent nerves containing ganglion cells with no atypia mainly located in the gallbladder mucosa. The neural nature of these components was confirmed by immunohistochemical labelling with antibodies specific for synaptophysin, glial fibrillary acidic protein, S100 protein and neurofilaments. Based on these findings, the lesion was diagnosed as ganglioneuromatosis. Reports of ganglioneuromatosis in animals have so far been restricted to the intestine. This is the first case of ganglioneuromatosis affecting the gallbladder in an animal in which no intestinal involvement was apparent.