Immunohistochemical Study of Gastrointestinal Stromal Tumors

ABSTRACT

Historically, gastrointestinal stroma tumors (GIST) have been considered as smooth muscle tumors, but the controversy over this histogenesis is provoked due to various results with utilizing immunohistochemical methods. In andeffort to further clarify the histogenesis of GIST, we performed the immunohistochemical study, as well as histopathologic reexamination, of 24 cases, all diagnosed as smooth muscle tumors of gastrointestinal tract, from Seoul Paik Hospital and Ewha University Hospital between 1980 and 1989, and the main results were as follows; 1) In the histopathologic features by light microscopic study, 11 benign and 13 malignant lesions (including one high grade malignancy and 12 low-grade malignant lesions) were disclosed. 2) In the immunohistochemical study, all tumors showed Vimentin positivity (100%), but no tumor showed S-100 protein positivity (0%), and 7 cases (29.1%) showed Desmin positivity. Positive reaction for Desmin made it possible to suggest that the histogenesis of GIST be in smooth muscle, and neurogenic origin would be excluded by all negativity for S-100 protein. In summary, we would like to conclude that GIST would be smooth muscle tumors on account of their morphological characteristics and their intramural location, but most of them appear poorly differentiated by immunohistochemical method.