低異型度分化型胃癌の病理学的特徴―肉眼像を含めて

Histopathological Features and Macroscopic Findings of Gastric Adenocarcinoma of Differentiated Type with Low-Grade Atypia

要旨　早期分化型胃腺癌の中から，無作為抽出された低異型度癌253病変，高異型度癌297病変を用い，低異型度癌の病理組織学的特徴，粘液形質発現，肉眼形態の特徴について，高異型度癌と比較検討した．低異型度癌において陥凹型が最も多かったが，高異型度癌と比較して隆起型の占める割合が高い傾向にあった．隆起型，平坦型，陥凹型を問わず，低異型度癌は高異型度癌に比較して褐色調の色調が減弱し，境界辺縁が不鮮明となりやすい傾向がみられた．隆起型と平坦型においては，これらの項目に関して低異型度癌と高異型度癌との間で有意差を認めた．粘液形質の種類と頻度に関して異型度別に差異はみられなかった．低異型度癌において胃型形質癌は，混合型形質癌および腸型形質癌と比較して，肉眼型を問わず，色調減弱および境界辺縁の不鮮明化が有意に高率であった．

　The aim of this study was to clarify the pathological features including macroscopic findings of gastric adenocarcinoma of differentiated type with low-grade atypia. We studied a randomly selected 253 lesions of low-grade gastric adenocarcinoma and 297 lesions of high-grade gastric adenocarcinoma.

　Depressed type carcinoma was most frequently observed both in low-grade carcinoma and high-grade carcinoma, and the frequency of protuberant type carcinoma was relatively higher in low-grade carcinoma compared with high-grade carcinoma. 　Carcinoma with low-grade atypia revealed a higher ratio of discolored（less brownish）lesions and unclearly-outlined lesions compared with high-grade carcinoma regardless of macroscopic type（protuberant type, flat type, and depressed type）. As for frequencty of mucin phenotype（gastric phenotype, gastrointestinal phenotype, and intestinal phenotype）, there was no difference between low-grade carcinoma and high-grade carcinoma. Gastric phenotype carcinoma of low-grade atypia revealed a significantly higher incidence in discolored surface and an unclear outline compared with gastrointestinal phenotype carcinoma and intestinal phenotype carcinoma.