4型大腸癌の臨床病理学的特徴とX線・内視鏡診断―浸潤様式との関係を中心に

Diffusely Infiltrating Colorectal Cancer: Correlation between Histologic Pattern and Radiographic or Endoscopic Findings

要旨　4型大腸癌32例を対象とし，X線・内視鏡像を検討した．対象は組織学上の浸潤様式からlymphangiosis（LA）型24例，scirrhous（SC）型4例，muconodular（MN）型2例，inflammatory（IF）型2例に分類可能であった．X線検査では，27例中24例（88.9％）で病変の全体像を評価可能であった．しかし，内視鏡検査では28例中7例（25.0％）で病変の口側大腸を，11例（39.3％）で狭窄内部を観察できたにすぎなかった．X線上SC型とIF型でLA型とMN型よりも管腔狭小化が高度で，LA型では口側ないし肛門側の横走ひだと敷石像の陽性率が高かった．切除標本上の腫瘍長径はX線所見上の長径と有意に相関した（r=0.74，p＜0.0001）が，LA型では両者が乖離する傾向を認めた（0.05＜p＜0.1）．以上より，4型大腸癌ではX線所見から浸潤様式が推測可能であること，LA型では浸潤範囲を慎重に決定すべきことが示唆された．

　We retrospectively investigated radiographic and endoscopic findings in 32 patients with diffusely infiltrating colorectal cancers. The cancers were divided into four types according to the histologic pattern of infiltration (lymphangiosis [LA] type, 24 cancers; scirrhous [SC] type, 4 cancers; muconodular [MN] type, 2 cancers; inflammatory [IF] type, 2 cancers). While colonoscopy was able to pass through the cancerous stenosis in only 7 of the 28 cases (25.0％), barium enema examination was able to depict the entire lesion in 24 of 27 cancers (88.9％). Observed radiographically, the stenosis was shown to be more severe in SC and IF types than in LA and MN types. However, transverse folds and cobblestone-like appearance were more frequently observed in the LA type than in other types. Although the longitudinal length of cancers determined by histology correlated well with that determined by radiography (r=0.74, p＜0.0001), there were cancers of LA type in which the length determined by these two methods was different according to which method was used. These findings suggest that in diffusely infiltrating cancers the histologic pattern of infiltration can be partly predicted by radiographic findings, but that the invasion length should be carefully determined, especially in the LA type.