Canine Gastric Adenocarcinoma

Abstract

In a retrospective study of 26 gastric adenocarcinomas of the dog, 17 were found to have histologic features of the diffuse type and nine of the intestinal type similar to those of the same tumor in man. The intestinal type was characterized by distinct glandular structures lined with well polarized cells at the primary and metastatic sites and mild desmoplastic reaction. Three subtypes with distinct histologic features (papillary, five; acinar, three; solid, one) were recognized in this group. Fourteen of the diffuse adenocarcinomas were characterized by random infiltration by neoplastic cells, singly or in clusters, often with signet ring cells and severe desmoplastic reaction. The remaining three diffuse adenocarcinomas also had recognizable acinar structures and were considered to be glandular subtypes of the diffuse type. In eight dogs there was a 7:1 male to female ratio for dogs with the intestinal type and in 16 dogs a 2:1 male to female ratio for dogs with the diffuse type. Two of the nine intestinal type of adenocarcinomas, but none of the diffuse tumors, had intraluminal growths. Metaplasia of gastric epithelium was seen in nearly half the tumors; this was more common in the intestinal type (six of nine). Different degrees of carcinomatosis were seen in 24 of 26 dogs. Regional lymph nodes were involved in the 20 dogs whose nodes were available for examination. Distant metastases were seen in 19 of 26 dogs; liver, lungs and adrenal glands were the most common sites. Various degrees of lymphoid cell infiltration, suggesting the antigenic quality of the neoplasms, were seen in 15 dogs. Additional neoplasms were seen in eight dogs.