gastrointestinal stromal tumor（GIST）の臨床病理―消化管間葉系腫瘍の概念の変遷とGISTの定義・臓器特異性を中心に

Clinical Pathology of Gastrointestinal Stromal Tumor (GIST): With Special Reference to Change of the Cencept of Gastrointestinal Mesenchymal Tumor (GIMT) and the Definition and Organ Specificity of GIST

要旨　消化管間葉系腫瘍(GIMT)251手術症例，特に間質腫瘍(狭義のGIST)105症例について，臨床病理学的立場から検討した．GIMTはRosai分類に従って平滑筋型137，神経型7，混成型2，中立型(狭義のGIST)105例に分類された．105例のGISTの発生部位は食道0，胃81，小腸16，大腸8例であり，またGIMT中に占めるGISTの割合も食道は他部位に比べて有意に低率であった．組織学的には良性19，境界領域22，悪性64腫瘍に類別されたが，それぞれの平均核分裂数は2.4，13.5，17.6個/50HPFであった．部位別の悪性腫瘍比率は胃54.3％，小腸75％，大腸100％であり，胃と大腸間には有意差を認めた．以上の結果から，GISTは食道には少なく，大腸では悪性腫瘍の比率が高いという臓器特異性を指摘した．併せてGIMTの概念の変遷，GISTの定義，悪性度の指標および組織発生について簡単に考察を加えた．

　A total of 251 operated cases of gastrointestinal mesenchymal tumor (GIMT) were studied. Special notice was made of 105 cases of stromal tumor (GIST in a narrow sense) which were analyzed from a clinico-pathological standpoint of view. Using Rosai's classification, the cases of GIMT were classified into 137 cases of smooth muscle type, 7 of neural type, 2 of combined smooth muscle-neural type, and 105 of uncommitted type (GIST in a narrow sense). The sites of the 105 lesions of GIST were the esophagus no cases, the stomach 81 cases, the small intestine 16 cases, and the large intestine 8 cases. The rate of GIST among all cases with GIMT was also significantly lower in the esophagus as compared with other sites. Histologically, the tumors were benign in 19 cases, intermediate in 22 cases, and malignant in 64 cases, and the average number of mitoses of those tumors was 2.4, 13.5, and 17.6/HPF, respectively. The rate of malignant tumor for each site of involvement was 54.3% in the stomach, 75% in the small intestine, and 100% in the large intestine, and a significant difference was noticed between the rates stomach and large intestine malignancy. From those results, it was pointed out that GIST was rare in the esophagus and that the rate of malignant tumors was very high in the large intestine. In addition, changes in the concept of GIMT and its definition as well as indices of maligancy and histogenesis of GIST were briefly described.