通常内視鏡・超音波内視鏡で深達度を過大評価した大腸m癌の1例

Overestimation of the Depth of Invasion in Colorectal Cancer, Report of a Case

要旨　深達度を過大評価したS状結腸のIIa＋IIc型腫瘍症例を供覧する．通常内視鏡所見で深い陥凹および不自然なひだ集中が認められたこと，超音波内視鏡検査で第3層の菲薄化所見が認められたことから粘膜下層深層までの浸潤を疑った．EMRを試みたがnon-lifting sign陽性であったため外科的切除を行った．組織学的検査の結果，深達度mの高分化型腺癌であった．拡大内視鏡では粘膜下層深層への浸潤を示唆する所見はなく，通常内視鏡および超音波内視鏡所見で粘膜下層深層への浸潤を示唆する所見が認められた原因は，腫瘍直下粘膜下層の線維化であると考えられた．

　Submucosally invasive colorectal cancer is associated with a risk of nodal involvement. The depth of invasion is one of the known risk factors for nodal metastasis. The assessment of the depth of invasion is made by means of conventional colonoscopy, magnifying chromoendoscopy and endoscopic ultrasonography. However, the findings obtained by these modalities are sometimes inconsistent with each other. Here we report a case with sigmoid colon carcinoma confined to the mucosa, for which the assessment of the depth of invasion was overestimated. Submucosal fibrosis is thought to bias the findings of conventional as well as of magnifying colonoscopy.

　1) Department of Surgery, Omiya Medical Center, Jichi Medical School, Saitama, Japan

　2) Department of Pathology, Omiya Medical Center, Jichi Mediacal School, Saitama, Japan

　3) Department of Endoscopy, Jichi Medical School, Tochigi, Japan