Synchronous adenocarcinoma and gastrointestinal stromal tumor in the stomach - report of two cases

Introduction Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor that occurs in the gastrointestinal tract, most commonly in the stomach or the small intestine. The surgery of the stomach is the dominant way of treatment of these tumors. The synchronous detection of adenocarcinoma and gastric GIST is not a very common condition, which is often diagnosed intraoperatively and has a significant impact on the prognosis of these patients. Outline of cases We herein report two cases of gastric GIST with synchronous adenocarcinoma tumors, which were detected incidentally, intraoperatively, while the patients were undergoing surgery for a primary gastric adenocarcinoma. The first case was of a 76-year-old female patient.The histopathological analysis of the operative specimen firstly showed a poorly differentiated advanced gastric adenocarcinoma. The second tumor, from the gastric serosa, was a spindle cell GIST of low risk. It was diffusely positive for DOG1, CD34, and CD117. Its proliferative index was established using the Ki67 antibody. The number of mitoses was one per 5 mm(2). The second case was of a 65-year-old male patient. The histopathological analysis revealed an early, well-differentiated, intestinal type adenocarcinoma of the gastric mucosa. The synchronous tumor from the serosa of the stomach was a spindle cell gastrointestinal stromal tumor (CD34, DOG1, and CD117 diffusely positive) of low risk. The proliferative index of this tumor, labeled with the Ki67 antibody, was very low. Necrosis was not present, nor was mitosis. Conclusion Synchronous adenocarcinomas and GIST of the stomach are not very commonly associated, and are usually detected intraoperatively and after an immunohistochemical analysis. Recognition of this condition has a very important role in a differential diagnosis and the exclusion of metastases of malignant tumor deposits. Based on the tumor severity, the radicalness of the surgical intervention is determined, which affects the outcome of these patients.