Diffuse Gastric Adenocarcinoma in a Bitch

Abstract

Background: Gastric neoplasms account for less than 1% of cases of neoplasia in dogs, making them a rare clinical finding. They predominantly occur in male dogs over 9 years of age. Clinical signs are typically nonspecific and they include vomiting, anorexia, and weight loss. Grossly, gastric tumors may appear either exophytic or sessile. Diagnosis is confirmed microscopically by the presence of non-cohesive neoplastic epithelial cells The objective of this report is to describe the macroscopic and microscopic characteristics of a case of diffuse poorly differentiated gastric adenocarcinoma localized in the cardia region of a 8-year-old bitch.

Case: A 8-year-old bitch French Bulldog presented with inappetence, regurgitation, and progressive weight loss. Physical examination revealed pale mucous membranes, an ulcerative lesion on the tongue, sialorrhea, and abdominal distension. An endoscopy was requested, which demonstrated mild gastritis. Further, a biopsy of the tongue revealed focally extensive ulcerative glossitis with granulation tissue formation. Despite medical management, the dog’s condition worsened, and euthanasia was elected after 2 months. Necropsy findings included a persistent ulcerated lesion on the tongue and a firm, whitish, transmural mass in the cardia region of the stomach. The gastric and mesenteric lymph nodes appeared reactive, and 3 mucosal ulcerations were observed in the stomach. Histopathological examination confirmed a diffuse infiltrative neoplastic proliferation of individual epithelial cells and small aggregates within a dense collagenous stroma in the stomach. Based on clinical, gross, and microscopic findings, a diagnosis of diffuse poorly differentiated gastric adenocarcinoma in the cardia region was established.

Discussion: Gastric adenocarcinoma is an uncommon malignancy in dogs, which typically affects male dogs older than 9 years of age. Most canine gastric tumors are epithelial and malignant, with adenocarcinomas representing 60% to 70% of cases. The gastric body, pylorus, and greater curvature are the most frequently involved regions, and lesions are often ulcerated and hemorrhagic, resulting in stenosis. In the present case, the patient was a 8-year-old bitch French Bulldog with a neoplasm located in the cardia region, and although the mass was firm and infiltrative, it was not ulcerated or hemorrhagic, highlighting its atypical presentation. Histologically, gastric carcinomas are characterized by infiltrative growth, extending from the mucosa to the serosa. The diffuse type, most commonly observed in dogs, is composed of highly anaplastic cells with prominent desmoplasia. In the present report, the neoplastic proliferation exhibited an infiltrative pattern with marked cellular and nuclear pleomorphism, and neoplastic emboli were frequently observed within lymphatic vessels. The prognosis for canine gastric carcinoma remains poor, with survival times ranging from 0 to 10 months after diagnosis. Definitive diagnosis in this case was achieved post mortem via histopathology, precluding the possibility of therapeutic intervention. Although no metastases were identified histologically or cytologically, the absence of immunohistochemical evaluation limits definitive conclusions regarding metastatic spread, particularly concerning the etiology of the tongue lesion.

Keywords: canine, histopathology, gastric neoplasia, neoplasm, tumor, carcinoma.

Título: Adenocarcinoma gástrico difuso em uma cadela

Descritores: canino, histopatologia, neoplasia gástrica, neoplasm, tumor, carcinoma.