Gastrointestinal stromal tumors the assessment of malignant potential

GISTS are the largest category of non-epithelial neoplasms of stomach and small bowel. Numerous immunohistochemical, ultrastructural and flow cytometry studies have been carried out for evaluation of prognostic factors which could predict malignant behaviour of these neoplasms. Tumor size of 5 cm and mitosis of 2/10 hpf were suggested as two important parameters which could predict the chances of recurrence and clinically aggressive course. The aim of this study is to examine predictive value of these two important parameters in assigning the tumors as high, intermediate and low risk groups. Using these two parameters we categorized 30 cases of GIST over a period of 6 years (1990-95) into low, intermediate and high risk groups and examined other features of these cases. Based on these two parameters alone we found that 4 cases each in low and intermediate group could be assigned to a higher risk group clinically as there were presence of adjacent organ infiltration, lymphatic emboli, serosal nodules, lymph node metastasis and transmural infiltration. Hence, other features like hemorrhage, necrosis and anaplasia should also be included in risk assessment. Metaplastic tissues like bone, cartilage and adipose tissues were seen only in high-risk categories.