消化管GISTの診断と悪性度の評価―超音波内視鏡検査と超音波内視鏡下穿刺吸引法

Diagnosis and Assessment of Malignancy for Digestive GIST―Endoscopic Ultrasonography and EUS-guided Fine Needle Aspiration

要旨　外科的切除されたGIST 27例（胃25例，十二指腸1例，大腸1例）のEUS像はA type 13例，B type 8例，C type 6例であった．病理組織像を対比すると，B typeの多くは腫瘤内に出血巣を認め，C type全例に腫瘤内に融解壊死の部分を認めた．EUS像ではC type（内部に無エコーの部分を有する例），あるいは内部エコーが不均一な例に悪性度が高かった．EUS-FNAはGIST 18例に実施され，吸引細胞診によりGISTを示唆された例は66.7％であった．十分な組織標本が採取され，生検標本として病理学的診断されたのは14例（77.8％）で，このうちGISTあるいはGIST疑いと診断された例は11例（78.6％）であった．両者を合わせたGISTとの診断は88.9％（16例/18例）であった．

　In 27 cases of GIST (25 cases of the stomach, one case of the duodenum, one case of the colon) operated on surgically, the EUS findings of the cases showed 13 cases of type A, eight cases of type B, and six cases of type C. Compared with the histological findings of specimens, the hemorrhage nest in the tumors was found in many cases of type B. Colliquative necrosis was observed in the tumors of all cases of type C. According to the analysis of EUS findings, cases of type C (cases in which was observed an anechoic area in the tumor) or cases showing a heterogeneous pattern of internal echo should be diagnosed as high-grade malignancy pathologically. EUS-FNA was performed in the 18 cases of GIST, and 12 cases (66.7％) were suspected of being GIST by cytology of EUS-FNA. In 14 cases (77.8％) enough tissue specimens were obtained and diagnosed by biopsy specimens for their pathology. In these cases, 11 cases (78.6％) were diagnosed as GIST or suspected GIST. The result of the total diagnosis, through cytology or biopsy of EUS-FNA, was that GIST was present in 88.9％ of the cases (16/18 cases).