Intestinal Mucinous Adenocarcinoma with Lymph Node Metastasis in a Cat

Corresponding Author: Handan Hilal Arslan Department of Internal Medicine, Faculty of Veterinary Medicine, Ondokuz Mayis University, Turkey E-mail: arslanhhilal@gmail.com Abstract: Intestinal adenocarcinoma is a malignant tumor. The most common clinical signs of gastrointestinal adenocarcinoma are depression, anorexia, loss of weight, vomiting, diarrhea or constipation due to obstruction. In cats, gastrointestinal adenocarcinomas are the most common non-hematopoietic gastrointestinal tumors and their frequency is higher in males. In this report, the case of an 8 year old male cat with adenocarcinoma that had metastasized to the lymph nodes is presented.


Introduction
Intestinaltumours are uncommon in cats, accounting for about 1% of all malignant feline neoplasms. Adenocarcinomas are the most common type of feline intestinal neoplasm (52%), followed by lymphosarcoma (21%) (Rivers et al., 1997).
Adenocarcinomas are malignant tumors of the glandular epithelium that differentiate from the crypts of Lieberkuhnand spread through the intramural or submucosallymphatics. These tumors are considered highly malignant, with frequent metastasis to the regional lymph nodes (Prater et al., 1999;Theilen and Madewell, 1979).
Gastrointestinal adenocarcinomas are the most frequently detected nonhematopoietic gastrointestinal tumors in cats (Turk et al., 1981). They can be seen in all segments of intestine but the ileum is the commonest site, where as adenocarcinoma is generally detected in the colon and duodenum of dogs (Patnaik et al., 1976).
The most frequent symptoms of gastrointestinal adenocarcinoma are lethargy, anorexia, loss of weight from 5 days to 6 months, vomiting, diarrhea and constipation (Patnaik et al., 1976).
Adenocarcinomacan cause partial or complete obstruction of the intestine (Head and Else, 1981). Obstructions can be seen in direct and indirect radiography after the administration of barium. A swollen, fluid-filled abdomen and palpable mass can occur as well (Patnaik et al., 1976). The tumors are often firm and white at the cut surface (Head and Else, 1981).
The subject of this case report is an eight year old, male cat with intestinal mucinous adenocarcinoma that had metastasized to the regional lymph nodes.

Description of Clinical Case
The eight year old, male cat was presented to our clinic with a constipation problem. The owner reported that a foreign body was diagnosed year earlier and the cat hadn't recovered after the treatment. Two weeks before presentation at our clinic, the owner observed anorexia, lethargy and weight loss. The cat was taken to a private veterinary clinic. Supportive treatment, which included fluid therapy, was administered for a week.
When the cat was brought to our faculty's clinic, a general examination was performed. The patient was severe dehydrated, the mucosal membranes were anemic and there was a brown nasal discharge. In the palpation, a relatively large, air and fluid filled structure was detected in the right lateral part of the abdomen. In addition, a solid mass of about 2 cm diameter was palpated in the abdomen. The body temperature was 36.5°C. Haematological analyses were performed and serum enzyme levels were checked. Direct and indirect radiography with barium sulphate were performed. The hematological analyses showed that the White Blood Cell count (WBC) (16.85 10 9 /L) and neutrophilcount (segmented) (14.38 10 9 /L) were slightly elevated, the lymphocyte count (0.93 10 9 /L) was slightly lower and the platelet count was much higher (1125 10 9 /L). In addition, the serum urea level was more than two times higher (98.8 mg dL −1 ) than the reference range and the creatinine level (2.3 mg dL −1 ) was slightly higher than the reference range.
In the direct radiography, the stomach, duodenum and proximal part of jejunum were enlarged Fig. 1 and the intestine was empty. In the contrast radiography with barium sulphate, at 0, 15, 30, 45, 60, 120, 180 min and 24 h, the contrast substance had moved just into the duodenum but no further.
In the ultrasonographic examination, the stomach was enlarged and full of fluid. Although the fluid was moving from the stomach to the duodenum, it couldn't pass on to the other parts of the intestine. In addition, thickening of the intestinal wall was detected.
Surgical intervention was deemed necessary. Laparotomy was performed on the cat under general anesthesia. The air and fluid was removed from the stomach and the internal surface of the stomach and intestine were checked for blockage. A mass which was solid but flexible was detected in the proximal part of the jejunum. It was 2.5-3 cm in length Fig. 2a and 2b. After the mass was totally removed and the peripheral nymph nodes, endwise anastomosis was performed.
Despite the full routine of intensive therapy for three days post-surgery, the patient deceased.
The intestinal mass and mesenteric lymph nodes were fixed in 10% neutral buffered formalin, embedded in paraffin wax, sliced at 5 µm intervals and stained with Hematoxylin-Eosin (HE) and Toluidin Blue (TB).
Microscopically, the tumor mass composed of neoplastic cells characterized by small acini and solid groups that produced mucin and infiltrated throughout the intestinal wall. There were scattered single cells and small groups of tumor cells that were mostly cubical or columnar, but many signet ring cells were also visible. Large extracellular mucin lakes replaced the normal intestinal tissues, especially in the muscular layer and mesentery. S Neoplastic cells showing signet ring characteristics had dark nuclei that were pushed to the cell periphery by mucin and showed many mitotic figures. Tumor cell emboli were seen in many lymphatic vessels and venules. There were necrotic changes in some areas of intestinal wall. The regional lymph node exhibited extensively metastasis showing microscopic features similar to those of the primary sites Fig. 3.
At the end of the pathological examination, adenocarsinoma was diagnosed in the mass and its peripheral lymph nodes.

Discussion and Conclusion
Intestinal adenocarcinoma occurs more rarely in cats than in humans and dogs. The frequency is higher in male cats than in females. Siamese and short hairdomestic cats are affected more than the other breeds. The mean age for the occurrence of intestinal adenocarcinoma is 11 years (5-17 years) (Patnaik et al., 1976;Cribb, 1988). The cat in ourcase was eight year old, male and a short hairdomestic breed. These characteristics put our patient in the high risk category for adenocarcinoma.
Cats with adenocarsinoma have usually had a long history of non-specific gastrointestinal disease symptoms such as weight loss and vomiting (Cribb, 1988). According to the reported cases, weight loss, anorexia, lethargy, vomiting, diarrhea or constipation are the predominant clinical signs of intestinal adenocarsinoma (Patnaik et al., 1976). The cat that is the subject of this case study had a number of these symptoms.
Abdominal radiography is helpful in diagnosing intestinal obstruction (Kosovsky et al., 1988). In indirect radiography, the contrast substance moved as far as the duodenum. The obstruction was subsequently determined with ultrasonographic examination to be in the jejunum region.
After intestinal resection and anastomosis, median survival time was reported to be only 2.5 months in cats (range: 0-24 months) (Cribb, 1988). That description covers the presented case.
In this case study, the mass was detected in the proximal part of the jejunum. The small intestine seems to be the most frequent location of gastrointestinal adenocarcinomain cats; the jejunum, ileum and ileocecocolic junctions are the most commonly affected sites (Kosovsky et al., 1988).
In cats, adenocarcinoma metastasised to the regional lymph nodes 45 and 50% of these occurred in the peritoneum or omentum; 8% were in the lungs; and 9% were in the abdominal organs, including the liver and spleen (Cribb, 1988). Metastasis to the regional lymph nodes also occurred in the cat in our study.
Adenocarcinomas can be classified into four histologically distinct groups, namely (1) carcinoma with solid groups of cells, (2) adenocarcinoma with solid and acinar cells, (3) papillary adenocarcinoma and (4) mucinous adenocarcinoma (Patnaik et al., 1976). After the histopathological evaluation of the mass in our case, it was identified as a mucinous adenocarcinoma.
In conclusion, differential diagnosis is very important in cats with non-specific gastrointestinal symptoms Veterinary clinicians should consider adenocarcinoma in cats with a long history of chronic gastrointestinal complaints such as symptoms that can include anorexia, lethargy, weight loss, vomiting and constipation.