The retrospective evaluation of gastrointestinal stromal tumor cases diagnosed between 2003-2014 at KTU of Medicine Department of Pathology

Gastrointestinal Stromal Tumor (GIST) stems from the interstitial cajal cells and is the most frequently observed mesenchymal tumor of the gastrointestinal system. In our study, 71 GIST cases that were diagnosed in KTU, Faculty of Medicine, Medical Pathology Department between 2003-2014 were assessed retrospectively by considering their demographic, histomorphological, immunohistochemical findings, risk grouping (Miettinen Classification) and Metastasis Characteristics. 41 of the seventy-one cases (57,7%) were female, and 30 (42,3%) were male patients; and the age range was 23-85. The mean age was 62. The tumor diameters were ≤ 2cm in 6 cases (9%); ˃ 2cm- ≤ 5cm in 23 cases (33%); ˃ 5cm- ≤ 10cm in 23 cases (%33) and ˃ 10cm in 18 cases (25%). The most frequent stomach localization was observed in 34 (47,9%) of the cases. In 43 of the cases (60,6%) the type of the tumors was fusiform; in 7 of them (9,9%) it was epithelioid; and in 21 (29,6%) the mixed type were observed. Ulcer was observed in 30 cases (42,3%), and necrosis was observed in 29 (41%) of them. The number of the mitosis in 50BBA was 5, and below 5 in 45 cases (63,4); and over 5 in 26 cases (36,6%). 66 cases (96%) were stained positively with CD117; 59 cases (83%) with CD34; 6 cases (8,4%) with desmine; and 14 cases (19,7%) with SMA; and 6 cases (8,4%) with S-100. The Ki-67 index was calculated as ≤ 10% in 39 cases (54,9%); and as ˃ 10% in 8 cases (11,3%). Metastasis was detected in 19 cases (26,8%). One (1,4%) case was considered in the "Insufficient Data" Group; 2 cases (2,8%) in "No Risks"; 3 cases (4,2%) in "Very Low Risk"; 18 cases in (25,4%) "Low Risk"; 15 cases (21,1%) in "Medium Risk"; and 31 cases (43,7%) in "High Risk" group. Statistically significant results were obtained between the number of the ulceration, necrosis, mitosis, risk groups, Ki-67 index and mitosis. No significant results were obtained between gender, age, localization, tumor diameter, cell type, cytological atypia, immunohistochemical markers (CD117, CD34, desmine, SMA, S-100, Ki-67) and the risk groups. As a conclusion, ulceration, necrosis and mitosis activity are important microscopic findings in defining the GIST risk groups. The strong relation between the high risk group and metastasis shows the importance of risk grouping in determining the malignity potential.