GIST in Saudi Arabia: multicentric histopathological genetic study of 75 surgically excised cases.

The availability of CD117 (Ckit) immunohistochemical testing in most hospital laboratories has facilitated the diagnosis of GIST in cKit positive cases. The aim of this study was to describe the histopathological variations of GIST in Saudi Arabia. The study involved analysis of paraffin blocks of 75 surgically excised GIST and GIST-like stromal tumors obtained from four major referral hospitals in Saudi Arabia (Riyadh Military Hospital, King Abdulaziz Medical City, King Faisal Specialist Hospital & Research Center and Aramco's hospital) between 1998 and 2009. Patient sex and age were noted in addition to the following tumor variables: size, site, histological grade and type, immunohistochemical profile and genetic analysis of the cKit mutation. The stomach was the commonest site for tumors and spindle cell type was the most frequently seen variant. Further sub classification of the histopathological type was made in order to recognize the morphological pattern of the tumor. The most common tumor grades seen were of low-risk and high-risk groups. There was one case of familial GISTparaganglioma syndrome and the youngest subject was an 8-year-old girl with high-risk spindle cell gastric GIST. Genetic study in 34 cases revealed exon 11 mutations in all of the cKit genes.