Gastrointestinal stromal tumours: An update

Gastrointestinal stromal tumours (GISTs) comprise the largest subset of mesenchymal tumours of the digestive tract. These tumours have been the subject of considerable debate in the literature regarding their histogenesis, criteria for diagnosis, prognostic features and biological behaviour.

The majority of GISTs express CD117 immunostaining and show various degrees of differentiation towards the phenotype of interstitial cell of Cajal.

Clinically and histologically, GISTs represent a spectrum that includes benign and malignant variants. The prediction of clinical behaviour is best achieved by evaluation of multiple parameters including clinical, morphological and cytogenetic features.

The recognition of the central role played by activating mutations of c-kit and platelet derived growth factor receptor alpha in the pathogenesis of GISTs and the introduction of STI-571, a receptor tyrosine kinase inhibitor that has proved extremely effective in the treatment of GISTs, have not only have focused attention on these tumours but also made it necessary to accurately define these tumours and separate them from other mesenchymal lesions. This review discusses the definition, histogenesis, epidemiology, clinical presentation, morphological and immunohistochemical features and the differential diagnosis of GISTs and addresses predictors of malignancy and management of GISTs.