Clinical and morphological features of gastrointestinal stromal tumors
Summary. Introduction. Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of digestive system. These tumors have usually indolent course, but in some cases can acquire malignant features. Aim. To investigate the main clinical and morphological features of GISTs with different location. Materials and methods. This study is based on retrospective analysis of case histories, histological samples stained with hematoxylin-eosin and immunohistochemical samples stained with CD117, CD34, DOG-1, SMA and CD56 from 100 patients, who were primary diagnosed with GIST and got surgical excision of this tumor in period from 2013 till 2019. The factor of inclusion in group was the ability to get follow up history of the patient within at least a year after surgery. Results. According to site the GISTs divided into GISTs of small intestine (38%), gastric GISTs (34%), GISTs of large intestine (27%) and 1 GIST of esophagus. Epithelioid GISTs were located in stomach only. These tumors were negative to CD34 and focally slightly positive to CD117. Some of them have shown mild expression of CD56 in single tumor cells. Nongastric GISTs have usually spindled morphology. Duodenal GISTs occurred in 5% of cases and were diagnosed as cancer of the head of pancreas before histology was not performed. Jejunal and ileac GISTs were larger than 5 cm in 100% of cases. The main number of advanced GISTs in our study were from this group. More than the half of patients with small intestinal GISTs didn’t have any symptoms of disease at all, anemia was found in third of cases. Colorectal GISTs present in 27% of cases. 92.6% of these tumors were <5cm and in third of cases associated with other malignancies. All nongastric GISTs demonstrated marked expression of CD117, DOG-1 and in 68.2% of cases CD34. The mild expression of SMA was found in 12 tumors (12%). All these GISTs were spindled. Nongastric GISTs have a tendency to relapse in period from 1 till 3 tears oftener than gastric GISTs. Conclusions. Small intestinal GISTs in our study were usually larger, asymptomatic, but demonstrated more aggressive behavior. Colorectal GISTs were found in our study 5 times more often than in data given by WHO and third of cases were associated with other tumors. This data can be used for following study of oncogenesis of these group of colorectal GISTs. Almost all nongastric GISTs had spindle cell morphology and showed good expression of CD117 and DOG-1. Epithelioid GISTs were characterized by gastric location, mild focal expression of CD117 and negative reaction to CD34.
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