空腸gastrointestinal stromal tumorの1例―造影超音波検査所見を中心に

Jejunal GIST in which Contrast-enhanced Ultrasonography was Useful for Diagnosis, Report of a Case

要旨　症例は74歳，男性．糖尿病で入院した際にスクリーニング目的で実施した腹部超音波検査で最大径46mmで一部に嚢胞性変化を伴う腫瘤が見い出された．超音波カラードプラで辺縁部に血流シグナルを認め，CT，MRIでも辺縁部にのみ造影効果を認めた．Levovist^®造影超音波では造影早期より強く辺縁部が濃染し，内部には造影効果はみられなかった．これらの所見から血流が豊富な腫瘍であり，小腸X線で空腸から発生し壁外に大きく発育した腫瘍であることが判明したため，gastrointestinal stromal tumor（GIST）と診断し腫瘍摘出術を行った．腫瘍の内部は変性した腫瘍組織と血液成分が充満した空洞より成り，辺縁部は組織学的にc-kit陽性の紡錘形細胞で構成されていることからGISTと診断した．腹部超音波，造影超音波は侵襲がなく，GISTのような腹部腫瘍に対して存在診断から質的診断まで非常に有用な検査と考えられた．

　A 74-year-old male was admitted for control of diabetus mellitus. Abdominal ultrasonography (US) for screening revealed an abdominal mass of 46 mm in diameter with cystic changes；color doppler, contrast enhanced CT and MRI demonstrated abundant blood flow only in the periphery of the mass lesion. Contrast-enhanced US (CEUS) using Levovist^® demonstrated that the peripheral area of the tumor was strongly enhanced on the early vascular image, but the central area was not enhanced at all. Enteroclysis revealed a submucosal tumor originating from the proximal jejunum. These finding suggested the diagnosis of gastrointestinal stromal tumor (GIST). Surgical resection of the tumor was carried out. Histological findings revealed that the peripheral area of this tumor was composed of spindle shaped cells which were positive for c-kit staining. These findings confirmed the diagnosis of GIST. US and CEUS are considered useful as a noninvasive diagnostic modality for GIST.