J Vet Clin 29(2) : 169-172 (2012)
169
Gastric Adenoma in the Pyloric Outflow Tract of a Shih-tzu Dog
Hee-Chun Lee, Do-Hyung Kwon, Jong-Hyun Moon, Young-Ki Kim, Kyu-Woan Cho, Byeong-Teck Kang*, Keum-Soon Im**, Jung-Hyang Sur** and Dong-In Jung1
Research Institute of Life Sciences, Gyeongsang National University, Jinju 660-701, Korea
*Laboratory of Veterinary Dermatology and Neurology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk, 361-763, Korea
**Department of Pathobiology, Small Animal Tumor Diagnostic Center, College of Veterinary Medicine, Konkuk University, Seoul 143-701, Korea
(Accepted: April 12, 2012)
Abstract : A 12-year-old castrated male Shih-tzu dog presented with vomiting, anorexia, and weight loss. The patient’s medical history and hematological, radiographic, ultrasonographic, and endoscopic findings were used for diagnosis.
The patient’s medical history showed that he was being treated for chronic kidney disease since a few weeks. The serum biochemical analysis showed moderate azotemia. However, abdominal radiographic and ultrasonographic findings showed the presence of a mass in the pylorus area of the stomach. On gastrointestinal endoscopic examination, the proliferative mass was found in the pyloric antrum. The histopathological results of the endoscopic biopsy specimen indicated that it was strongly suspected a gastric adenoma; therefore, we surgically excised the pyloric outflow region via a Y-U pyloroplasty. The histopathological examination of the surgically excised specimen also indicated that the mass was a gastric adenoma. After surgical treatment, the patient’s condition improved gradually, and the clinical symptoms diminished in approximately 3 weeks after surgery. The patient’s condition was well controlled until recently, i.e., 18 months after surgery. This case report describes the clinical findings, imaging characteristics, endoscopic findings, and histopathological features of a gastric adenoma in the pyloric outflow tract of a dog.
Key words : gastric adenoma, dog, endoscopy.
Introduction
Tumors do not commonly occur in the gastrointestinal tract of domestic animals. In dogs, gastrointestinal tract tumors account for less than 1% of all canine tumors (9,12). In dogs, adenocarcinoma, carcinoma, leiomyoma, leiomyosarcoma, fi- brosarcoma, lymphoma, and extramedullary plasmacytoma are the most commonly reported gastrointestinal tract tumors (3,7,9,12,13). According to a study on canine gastrointesti- nal neoplasms, malignant gastric tumors are more common than benign gastric tumors (12,13). Benign gastric tumors rarely occur in dogs; gastric adenomas and leiomyomas consti- tute most of the gastric tumors in dogs (4,8,9).
This report describes the clinical findings, imaging charac- teristics, endoscopic findings, and histopathological features of a gastric adenoma in the pyloric outflow tract of a dog.
Case
A 12-year-old castrated male Shih-tzu dog presented with vomiting, anorexia, and weight loss. The patient’s medical
history showed that he was being treated for chronic kidney disease since many weeks. On physical examination, the patient showed mild depression and dehydration. His com- plete blood count did not show any remarkable findings, but the biochemical panel results showed mild hyperkalemia and moderate azotemia (Blood urea nitrogen; 60 mg/dl (normal; 7- 29 mg/dl), creatinine; 2.2 mg/dl (normal; 0.5-1.8 mg/dl), potas- sium; 5.9 mmol/L (normal; 3.5-5.8 mmol/L)). The thoracic radiographic findings were normal. However, lateral survey
1Corresponding author.
E-mail: jungdi@gnu.ac.kr
Fig 1. Abdomial survey lateral radiography of the patient. A large, homogeneous soft tissue opacity of oval to round shaped mass (arrows) is visible in the cranio-ventral region.
170 Hee-Chun Lee et al.
radiography of the abdomen showed homogeneous soft tissue opacity because of a large oval-to-round mass in the cranio- ventral region (Fig 1). Abdominal ultrasonography showed distension of the stomach with food, fluid and gas. And hypertrophied muscular and mucosal layers in the pyloric region were identified (Fig 2A and 2B). We suspected this gastric change to be an indication of hyperplasia or a tumor.
Therefore, we performed gastrointestinal endoscopic exami- nation. The results showed a small amount of digested blood in the pyloric antrum, and a proliferative mass that occluded most of the pyloric orifice was found in the pylorus (Fig 3A).
The other regions in the gastric wall and duodenal wall were normal. Endoscopic biopsy samples from the gastric mass were obtained for histopathological examination (Fig 3B).
After endoscopic examination, the patient was given fluid ther- apy for a few days to control the azotemia. Although the azotemia was well controlled with the fluid therapy, his clinical symptoms, including vomiting and anorexia, did not improve.
Histopathological examination of the biopsy sample indi- cated that it was strongly suspected a gastric adenoma (Fig 4A and B); therefore, we surgically excised the pyloric outflow region via a Y-U pyloroplasty. The histopathological examina- tion of the surgically excised tumor specimen confirmed that the tumor was a papillotubular type gastric adenoma (Fig 4C
and D). Follow-up abdominal ultrasonography showed that the movement in the gastric pyloric outflow tract gradually improved, and the thickening of the gastric wall in the pyloric region decreased. For 3 weeks, the patient was administered parenteral nutrition and fluid therapy. Three weeks after the surgery, the patient was allowed a liquid diet and did not expe- rience vomiting and anorexia. The patient’s condition was well controlled until recently, i.e., more than 18 months after sur- gery.
Discussion
Gastric adenomas are extremely rare in dogs and also rare in humans (8,14). None of the dog breeds are predisposed to gas- tric neoplasms, including adenomas (13). All types of gastric Fig 2. Abdominal ultrasonographic findings of the patient. Fig 2A and 2B indicates that hypertrophied muscular and mucosal layers are present at the pylorus.
Fig 3. Gastrointestinal endoscopic findings of the patient. Endo- scopic view of the pyloric antrum region demonstrates smooth- walled proliferative mass which is occluding most of the pyloric orifice (A). Biopsy specimens from the gastric mass are obtained using endoscopic biopsy forcep (B).
Fig 4. Histopathological profiles of endoscopic biopsy specimen (A & B) and surgical excision specimen (C & D). A, B: Gastric adenoma suspected. Pyloric gland hyperplasia can be seen, but structural change and neoplastic proliferation of pyloric gland also exist. Enlarged nuclei of epithelial origin is exist (H & E: A; × 200, B; × 400). C, D: Papillotubular type gastric adenoma. Irregularly arranged glands composed of high-grade dysplastic epithelial cells.
Epithelial cells show neoplastic changes (papillotubular shape) (H & E: C; × 100, D; × 400).
Gastric Adenoma in the Pyloric Outflow Tract of a Shih-tzu Dog 171
neoplasms occur more frequently in male dogs, but adenomas occur more frequently in female dogs (13). Gastric adenomas occur in dogs older than 5 years and seem to occur more com- monly in the pyloric antrum mucosa (2,4,10,11,13).
In dogs, the clinical symptoms of gastric tumors vary depending on the location of the tumors; however, they are usually asymptomatic until the disease has advanced (4,10).
In dogs with gastric neoplasia, the most common symptoms reported are vomiting, anorexia, and weight loss (14). Vomit- ing is caused by gastric outflow obstruction and weight loss by nutrient loss or cancer cachexia syndrome (4,10). In the present patient, vomiting and progressive weight loss due to the functional obstruction of the pylorus by the tumor were the main clinical symptoms.
The diagnosis of gastric tumors is based on clinical presenta- tion and imaging study results and is confirmed by histopatho- logical examination (4,10). Radiography and ultrasonography of the stomach have also been used for diagnosing gastric tumors (10). In this patient, we suspected the presence of gas- tric tumor on the basis of abdominal radiographic and ultra- sonographic findings.
Endoscopy is a noninvasive and useful diagnostic tool for observing macroscopic changes in the gastrointestinal tract and for obtaining specimens for histopathological examina- tion. However, endoscopy does not help in the diagnosis of diseases that involve the submucosal, muscularis, or serosal layers of the gastrointestinal tract, and the biopsy forceps used cannot obtain small specimens of the mucosal layer.
Although endoscopic diagnosis of gastric tumors has some limitations, endoscopy is generally considered as one of the best tools for observing gastrointestinal tract diseases, includ- ing tumors. In the present case, the endoscopic examination showed the presence of a proliferative mass occluding most of the pyloric orifice, and histopathological examination of the specimen obtained using endoscopic biopsy forceps allowed for the diagnosis of gastric adenoma. Before surgery, histopatho- logical confirmation might be important for deciding the surgi- cal approach. We suggest that the use of Y-U pyloroplasty as the surgical approach should be decided on the basis of the endoscopic biopsy results obtained.
Gastric surgery, chemotherapy, and radiation therapy can be used to treat gastric neoplasia (5). Previous studies (5,16) have reported that radiation therapy is not a suitable treat- ment option for gastric tumors because of poor tolerance of radiation by the surrounding organs (6). The results of a recent study (15) involving 3 dogs with gastric adenocarcinoma sug- gested the beneficial effects of chemotherapy after surgical treatment in such cases; however, generally dogs with gastric tumors may show little or no improvement with chemotherapy, except in cases of gastric lymphoma (1). Partial gastrectomy, pylorectomy with gastroduodenostomy, partial gastrectomy with gastrojejunostomy, and pyloroplasty have been indicated for treating gastric neoplasia. The choice of procedures depends on the characteristics (i.e., malignant or benign), location, and size of the tumor (5). Pyroloplasty may be indicated for benign
gastric tumors, especially for tumors with gastric outflow obstruction (5). The present patient had a gastric adenoma in the pyloric outflow tract, and therefore, we performed Y-U pyloroplasty.
The prognosis of gastric tumors is generally poor. The mean survival time of patients with a malignant gastric tumor, such as adenocarcinoma, has been reported to be less than 6 months after diagnosis, because of recurrence or metastasis (15). Another study reported that the median survival time of dogs who had gastric carcinoma and were treated with surgery was 72 days (6). However, the prognosis for benign gastric tumors is relatively good, if appropriate surgical excision is performed (6). The present patient was diagnosed with gastric adenoma when the initially obtained endoscopic biopsy speci- men was histopathologically examined; the diagnosis was con- firmed on histopathological examination of the surgically excised specimen. Therefore, the clinical symptoms of the patient were well controlled and diminished after surgery until recently, i.e., more than 18 months after surgery.
This case report describes clinical findings with prognosis after surgical treatment, imaging characteristics, endoscopic findings, and histopathological features of a gastric adenoma in the pyloric outflow tract in a dog.
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시츄견에서 위유문부에서 발생한 위선종 증례
이희천·권도형·문종현·김영기·조규완·강병택*·임금순**·서정향**·정동인1
경상대학교 생명과학연구원, *충북대학교 수의과대학, **건국대학교 수의병리학교실
요 약 : 12살의 중성화된 수컷 시츄견이 구토, 식욕부전, 체중감소의 증상으로 내원하였다. 병력청취, 혈액검사, 방사 선검사, 초음파검사, 내시경검사가 진단을 위해 시행되었다. 병력청취에 따르면, 환자는 몇 주 전부터 만성신부전증 치 료를 받고 있었다. 혈청화학검사에서 환자는 고질소혈증을 보였고 복부 방사선검사와 초음파검사에서 위의 유문부 종 괴를 확인하였다. 위 내시경 검사에서는 유문방의 증식성 종괴가 관찰되었다. 내시경적 생검 후 조직병리학적 검사결 과는 위선종이였고 이 결과에 따라 수술적 처치(유문 배출부위의 절제와 Y-U 유문성형술)를 실시하였다. 수술 후 두 번째 조직병리학적 검사결과 또한 위선종이였다. 술 후, 환자는 점차 호전되었고, 임상증상은 술 후 3주 후 사라졌다.
환자의 상태는 현재까지 잘 유지되고 있다.
주요어 : 위선종, 개, 내시경
