A. K. Patnaik

Canine Gastrointestinal Neoplasms

In a review of 10 270 canine necropsies, 55 neoplasms of the stomach and 64 neoplasms of the small and large intestines were diagnosed. A significant number of these neoplasms were malignant (P < 0.005) and epithelial (P < 0.005). Adenocarcinomas of gastric and intestinal origin were in dogs younger than the average age of 10 years. Average age for dogs with connective tissue neoplasms was higher than that for those with adenocarcinomas, and there was a difference in median ages of the various types of neoplasms. There was a higher percentage (65%) of gastric and intestinal adenocarcinomas in male dogs, whereas leiomyosarcomas of the intestines were more frequent in female dogs. Although no breed predisposition was found in dogs with gastric neoplasms, a significant number of the intestinal neoplasms (P < 0.005), especially the adenocarcinomas, occurred in the Collie (P < 0.05) and German Shepherd (P < 0.05) breeds. Twenty-six percent of the leiomyosarcomas also occurred in the German Shepherds. Half of the gastric adenocarcinomas occurred in the pyloric region (P < 0.005), and the greater curvature was the next most common site. The rectum was the most common site of intestinal adenocarcinomas, then the colon and duodenum. Leiomyosarcomas were more frequent in the intestines and occurred more commonly at sites where adenocarcinomas were less frequent. In contrast to all other types of intestinal neoplasms, primary lymphosarcomas of the intestines usually affected many segments. Four carcinoid tumors of the duodenum and colon were seen. Of the very rare neoplasms, there were two neurilemomas, both of the duodenum and having the same gross and histologic characteristics of this tumor in other locations.

Canine Hepatic Neoplasms: A Clinicopathologic Study

One hundred ten primary hepatic neoplasms, excluding hematopoietic and vascular tumors, were diagnosed in 12,245 canine necropsies. Included were 55 hepatocellular carcinomas, 24 bile duct carcinomas, 2 combined hepatocellular and cholangiocarcinomas, 15 carcinoids and 14 sarcomas. A majority of the dogs with hepatocellular carcinoma (80%), bile duct carcinoma (65%) and sarcoma (61%) were 10 years old or older; 71% of the dogs with carcinoid were under 10 years old. Hepatocellular carcinoma and sarcoma occurred more often in males, bile duct carcinoma in females, and no sex predisposition was found in dogs with carcinoid. All dogs had hematologic and biochemical abnormalities relating to liver function. The aspartate amino transferase/alanine amino transferase ratio was less than one in cases of hepatocellular carcinoma and bile duct carcinoma, and more than one in cases of carcinoid and sarcoma. A massive lesion in one of the liver lobes was the most common gross morphologic feature in cases of hepatocellular carcinoma and bile duct carcinoma, with the left lateral lobe affected most often. In cases of carcinoid, most of the lesions were diffuse. The most common sites of metastases were lymph nodes and lungs for hepatocellular carcinoma and bile duct carcinoma, lymph nodes and peritoneum for carcinoid, and spleen for sarcoma.

Canine hepatocellular carcinoma.

In a study of 110 primary hepatic neoplasms in dogs, 55 hepatocellular carcinomas and two combined hepatocellular and cholangiocarcinomas were diagnosed. These neoplasms were classified into the following 11 groups based on histo-architectural pattern: trabecular, peliod, cobblestone, peritheliomatous, anaplastic, pseudoglandular, pleomorphic, scirrhous, clear cell, solid, and combined hepatocellular and cholangiocarcinoma. The neoplastic hepatocytes varied from almost normal to highly anaplastic spindle cells. Pleomorphic and giant cells were common in some groups, rare or absent in others. Metastasis was found in 61% (35 of 57 dogs), with varied frequencies in the different groups. Cirrhosis was found in only 7% (4 of 57), in contrast to a much higher percent in man, indicating the possibility of a different pathogenesis in the dog.

A Morphologic and Immunocytochemical Study of Hepatic Neoplasms in Cats

A retrospective study was done of 47 neoplasms of the hepatic and biliary systems from 47 cats brought to The Animal Medical Center over a period of 10 years (1980 to 1989). Histologic examination of specimens taken at necropsy revealed that 87% (41/47) of the hepatic neoplasms were epithelial and 13% (6/47) were nonepithelial. Of the epithelial tumors, 25/47 (53%) were of intrahepatic bile duct origin, 9/47 (19%) were of hepatocellular origin, 5/47 (11%) involved the extrahepatic bile ducts, and 2/47 (4%) were adenocarcinomas of the gall bladder. Of the nonepithelial neoplasms, hemangiosarcomas were more common, 5/47 (11%), than leiomyosarcomas, 1/47 (2%). Multiple liver lobes were involved in 21/34 (62%) of the epithelial and all six of the nonepithelial intrahepatic neoplasms. Most of the bile duct adenocarcinomas (6/9) were predominantly characterized by acinar structures with mucin production, diffuse necrosis, and little desmoplasia. The hepatocellular carcinomas were characterized by three patterns—trabecular (five tumors), pseudoglandular pattern (two tumors), and anaplastic (one tumor). The hepatic carcinoid was characterized by various-sized groups of acinar and rosettelike structures, some with lumens, separated by thin fibrovascular stroma. The extrahepatic bile duct adenocarcinomas (4/4) were acinopapillary with moderate desmosplasia, whereas the adenocarcinomas of the gall bladder had elongated tubular structures lined by anaplastic cells and a severe desmoplastic reaction. The neuroendocrine carcinoma of the extrahepatic bile duct, the hemangiosarcomas, and the leiomyosarcoma had morphologic features characteristic of these neoplasms. Two of the 16 (13%) bile duct adenomas had anaplastic and precancerous changes. Residual benign components were seen in 10/15 (67%) of the biliary adenocarcinomas, 4/9 (44%) of the intrahepatic bile duct adenocarcinomas, and all of the extrahepatic bile duct adenocarcinomas and gall bladder adenocarcinomas. Results of immunohistochemical studies of the biliary neoplasms were similar to those described in studies of biliary neoplasms in human beings. Results of this study revealed that the frequency of different types of hepatic neoplasms in cats varied from that seen in dogs and human beings, but the morphologic features were comparable.

Canine intestinal adenocarcinoma and carcinoid.

Thirty-one of 35 canine intestinal neoplasms were adenocarcinomas and four were carcinoids. Acinar, solid, papillary and mucinous adenocarcinomas were seen. Acinar and papillary adenocarcinomas were more common in the duodenum, colon and rectum. Papillary adenocarcinomas involved longer segments of the intestine. Mucinous adenocarcinomas were in all segments of the intestines but were more frequent in the jejunum. The only signet ring cell carcinoma occurred in the duodenum. Carcinoids occurred equally in the duodenum and colon. Half the rectal tumors showed transition from benign polypoid lesions to adenocarcinomas. Hyperplasia, branching of crypts, increase in goblet cells, and glandular fusion (some cells with anaplasia) were severe in the mucosa adjoining all neoplastic tissue. Local invasion was seen in 32 dogs. Lymph node, lungs, liver and intestinal wall were the most common sites of metastases. Half of the metastases in the liver were from carcinoids and were diffuse.

Canine Hepatic Carcinoids

In 110 primary hepatic neoplasms in the dog, 15 carcinoids were diagnosed. Diffuse involvement of all liver lobes with severe hemorrhage and necrosis was seen in all cases. The neoplasms had three distinct histologic patterns: solid nests; cords or ribbons; and an alveolar pattern with rosettes. In all three groups there was fibrovascular stroma that was hyalinized, mineralized, and thick in some places. The neoplastic cells were relatively uniform, polygonal to spindle-shaped, with eosinophilic, granular cytoplasm and vesiculated nuclei. Mitotic activity varied among the three groups. Argyrophilia was seen in all specimens stained with modified Grimelius stain. Metastasis occurred in 14 of 15 dogs (93.3%); the peritoneal wall and adjoining lymph nodes were the most common sites.

Canine Gastric Adenocarcinoma

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.

Feline Intestinal Adenocarcinoma A Clinicopathologic Study of 22 Cases

Twenty-two cases of intestinal adenocarcinoma were diagnosed in an 11-year survey of 3145 feline necropsies. Histologically, tumors were grouped into four classes: (1) carcinoma with solid groups of cells, (2) adenocarcinoma with solid and acinar cells, (3) papillary adenocarcinoma, and (4) mucinous adenocarcinoma. Tumors were commonest in the ileum. Connective tissue, as well as epithelial metaplasia, were associated more often in this group of intestinal adenocarcinomas than seen before. Hypertrophy and hyperplasia of muscular layers of the unaffected sections of intestines were seen in most of the small bowel and in half of the large bowel carcinomas in this series.

Canine Bile Duct Carcinoma

Twenty-four adenocarcinomas of the hepatobiliary system were found among 110 primary hepatic neoplasms; 22 of these were intrahepatic, one involved the extrahepatic bile duct and one the gall bladder. Histologically, 10 intrahepatic neoplasms were classified as cholangiocarcinoma, and 12 as bile duct cystadenocarcinoma. The former were characterized by tubular structures lined by anaplastic cuboidal or columnar cells with diffuse fibrous stroma, and the latter by multiple cystic structures with papillary and solid areas. Half the bile duct cystadenocarcinomas showed benign cysts and transition to adenocarcinoma. This was seen in only one case of cholangiocarcinoma. The extrahepatic bile duct carcinoma was characterized by tubular structures lined with flattened cuboidal cells with scant stroma. The gall bladder adenocarcinoma contained many acinar structures lined with columnar or cuboidal cells and separated by thin stroma. Distant metastasis was found in 87.5% (21 of 24) of the bile duct adenocarcinomas; the lymph nodes, lungs and peritoneum were the common sites of metastasis.

Canine Sinonasal Skeletal Neoplasms: Chondrosarcomas and Osteosarcomas

We studied 34 chondrosarcomas and 17 osteosarcomas among 285 sinonasal neoplasms in the dog. Mesenchymal chondrosarcomas (24) were more common than ordinary chondrosarcomas. Ultrastructural studies done in one case confirmed mesenchymal chondrosarcoma. Of the osteosarcomas, fibroblastic osteosarcoma (7) was the most common. In contrast to non-sinonasal skeletal neoplasms which are composed mostly (80%) of osteosarcomas, chondrosarcomas (66%) and mesenchymal chondrosarcomas (47%) were predominant among the sinonasal skeletal neoplasms of this study. The average age (ten years) of the dogs with sinonasal osteosarcoma was higher than that of dogs with non-sinonasal skeletal osteosarcoma, and there was a distinct male predominance in the dogs with osteosarcoma and chondrosarcoma. Large breed dogs and boxers, frequently affected with skeletal neoplasms, were not affected commonly with sinonasal osteosarcoma. The frequency of metastasis in the dogs with chondrosarcoma and osteosarcoma was much lower than that seen in dogs with nonsinonasal skeletal neoplasms.