Abstract
Twelve patients with gastrointestinal stromal tumors (GIST), in a broad sense, were analyzed to elucidate the clinical significance and problems of immunohistochemical study. Malignant potentials were classified into three degrees by tumor size and mitotic rate. Three patients with the normal cellular type, grade I, showed the same staining as the proper muscle. The other 9 patients had increased staining of vimentin and CD34 in comparison with the proper muscle. Two patients with the uncommitted type, grade I, were judged to have immature tumors considering the low malignant potential. Two patients with the combined type and one with the smooth muscle type with α-SMA 3 (+) and desmin 3 (+), grade II or III, were judged to have mature tumors. However, malignant potential could not be judged from immunohistochemical findings alone. The above results indicate that clinical evaluation of immunohistochemical findings of GIST can initially be clarified by making an assessment with definite grading of malignant potential.
