A pathomorphologic and immunohistochemical study on 54 cases of gastrointestinal stromal tumors

Objective To investigate the histopathological and immunohistochemical features of gastrointestinal stromal tumors(GIST).Methods Light microscope was used to study the morphologic characteristics of 54 cases of GIST,the expression of CD 117(c-kit),CD 34,vimentin,SMA,Desmin S-100protein were detected in all the cases with EnVision immunohistochemical method.Results 54 cases of GIST with their ages ranged 35 to 85 years(mean 58 years).The tumor cells were spindle, epithelioid or both in different proportion,arranged in interlacing fascides,palisading,whirling,alveolar and diffusing sheets.The tumors were composed of spindle cells(38 cases)or epithelioid cells(5 cases)or both (11 cases).Ten cases were benign,14 cases potentially malignant and 30 cases malignant. Immunohistochemically,CD 117 and CD 34 showed diffuse strong expression.The positive results accounted for 94.4% and 77.8% respsctively.Vimentin was positive in all cases.Conclusion GIST predominantly occurred in middle aged or older patients.The tumor cells had varied types and arrangements.Under light microscope,some of them were difficult to be differentiated from leiomyoma and schwannoma.Combined determination of the antibodies such as CD 117,CD 34 and vimentin is helpful for the differential diagnosis of GIST.