Tumor carcinoide na vesícula biliar em cão / Carcinoid gallbladder tumor in a dog

ABSTRACT

Carcinoid is a neoplasia that arises from dispersed cells of the neuroendocrine system. This tumor is uncommon in animals, and its occurrence in the gallbladder is rare. A male Basset Hound dog's corpse was taken to the Univerdade Federal de Minas Gerais to be analyzed by the Veterinary Pathology sector, without a description of its previous history. Necropsy revealed the presence of pale oral, ocular and penile mucous membranes. The gallbladder had a thickened wall and a dilated lumen, which was filled with dark and lumpy bile. Its mucosa had a whitish-red nodule, with solid and friable areas. Microscopically, there was a focal neoplastic proliferation, which wasn't encapsulated and had imprecise limits, which cells were distributed in a solid pattern and separated by a delicate fibrovascular stroma. The neoplastic cells presented oval or round shaped nucleus, which had a chromatin predominantly loose, and one or two nucleoli. Their cytoplasm was moderately abundant, and in most of the cells it was eosinophilic, granular, and had well-defined limits. Using the Grimelius coloration, neoplastic cells' cytoplasmic granules stained brownish or black, confirming the neuroendocrine origin of the neoplasia. Based on the macroscopic and microscopic findings, the diagnosis of a gallbladder carcinoid was established.(AU)