Clinicopathologic spectrum of gastro intestinal stromal tumours - Experience at a tertiary care center

Context: Accurate diagnosis of Gastrointestinal stromal tumors (GISTs) and categorization of risk groups is crucial in the wake of targeted drug therapy. Aim: This study was undertaken to obtain insight into the clinicopathologic features of GISTs.
Materials and Methods: Retrospective study of 20 cases of c-KIT (CD 117) positive GISTs .Various histologic parameters were studied. Immunohistochemical panel included CD-34, Smooth muscle actin, S-100, Desmin, and Vimentin. Risk categorization was done as per standard protocol. Clinical details and follow up were retrieved from cases files.
Results: Of the total 20 cases, 15 were males. The mean age of presentation was 52 years. 50 % of the cases presented with gastro intestinal bleeding .The cases were categorized as high risk (60%), intermediate risk (20%), low risk (15%) and very low risk (5%). Stomach and small intestine were commonly involved and in 6 of the cases there were metastatic nodules in the mesentery/omentum/ peritoneum. Spindle cell morphology was the commonest histological pattern (55%). Nuclear pleomorphism, perivascular whorling, mucosal and fat invasion were seen only in the high risk group. CD-34, SMA and S-100 were positive in 90%, 30%, and 10% of the cases, respectively, with consistent Desmin negativity.
Conclusions: Cases of GISTs in our clinical setting presented a decade earlier and mostly belonged to the high risk group. Certain histological features such as necrosis, and perivascular whorling were more commonly associated with the high risk groups.

Keywords
c-KIT, CD117, gastrointestinal stromal tumor, immunohistochemistry, pathology