Gastrointestinal stromal tumors: clinicopathological and immunohistochemical features.

OBJECTIVES To study the clinicopathological and immunohistochemical features of gastrointestinal stromal tumors (GISTs) in Kuwait. MATERIALS AND METHODS Hematoxylin- and eosin-stained sections of primary gastrointestinal mesenchymal tumors were reviewed. Immunohistochemical staining was performed using a panel of antibodies to determine muscle and neural differentiation, the incidence of CD117 and CD34 expression, as well as bcl-2 and cytokeratin expression. Each stain was interpreted as negative or positive. The staining intensity of positive cases was graded as weak, moderate or strong. RESULTS The age range was 25-80 with an average age of 54 and a male:female ratio of 3:2. The stomach was the most common site for these tumors, followed by the small intestine. Histologically, 46% were classified as malignant and 54% were benign. Most of the malignant tumors occurred in males, particularly in the stomach or small intestine. There was no significant difference in patient age between malignant and benign tumors. The most sensitive markers were muscle-specific actin for muscle differentiation and glial fibrillary acidic protein for neural differentiation. CD117 expression was seen in 81% and CD34 in 54% of all tumors. CONCLUSIONS The results of this study show that the stomach is the most common site for these tumors, that malignant tumors are more likely to occur in the small intestine than in the stomach, and that there is no difference between benign and malignant tumors with regard to age. Our findings are comparable to those of other workers, although our male:female ratio was slightly higher.