胃腫瘍性病変の拡大内視鏡診断―陥凹型上皮性腫瘍

Differential Diagnosis of Gastric Tumors Using Magnifying Endoscopy in the Diagnosis of Depressed Epithelial Tumors

要旨　陥凹型上皮性腫瘍（早期胃癌，腺腫）のNBI拡大内視鏡所見について検討した．10mm以下の早期胃癌分化型腺癌121例では41/121（34％）が血管パターン（網目状血管）を呈し，70/121（58％）が構造パターン内にらせん状渦巻き状の血管を伴うパターンであった．10mm以下の未分化型腺癌44例の検討では窩間部開大を呈した症例が21/44にみられ，うち18/21（86％）では癌は増殖帯のみに進展していた．構造パターンに渦巻き状の血管がみられたパターンは5例にみられ，4例が癌の浸潤は全層もしくは増殖帯から表層に浸潤する症例であった．cork-screw patternを呈した症例は18例あり，11/18（61％）が全層に浸潤する癌であった．生検で陥凹型腺腫であった26例について検討したところ，最終診断は13例が腺腫中等度異型，13例が高度異型，もしくは分化型癌であった．これらのうち14/26（54％）が網目状の血管パターンを呈し，癌と腺腫の鑑別は困難であった．構造パターンは12/26（46％）であり，うち5例が癌，もしくは高度異型であり，それらは構造パターン内の渦巻き状血管がみられ，癌と腺腫の鑑別に有用であると考えられた．

　We investigated the findings of magnifying NBI（narrow-band imaging）endoscopy in the diagnosis of depressed epithelial tumors（early gastric cancer and adenoma）. Of 121 cases with early differentiated gastric cancers of 10 mm or smaller, 41（34％）showed microvascular pattern（fine-network vessels）and 70（58％）showed corkscrew, whorl-like vascular pattern within the mucosal structure. In 44 cases with undifferentiated adenocarcinoma of 10 mm or smaller, opening of the pit and large-size pit structure was found in 21 cases, of which 18（86％）demonstrated cancer progression only to the proliferation layer. In 5 cases, corkscrew-patterned vessels were seen in the large-size pit and 4 of them were found to have adenocarcinoma invading the whole thickness of the gastric wall or spreading from the proliferation layer to the surface layer. Corkscrew pattern was found in 18 cases, of which 11（61％）were adenocarcinomas involving the whole thickness of the gastric mucosa. We then examined 26 cases in which biopsy revealed depressed adenomas. The final pathological diagnosis was adenoma of moderate atypia in 13 cases and adenoma of high-grade atypia or differentiated adenocarcinoma in the remaining 13 cases. Of these 26 cases, 14（54％）showed network-patterned vessels, making it difficult to differentiate between cancer and adenoma. Structural pattern was found in 12（46％）of 26 cases, and 5 of them showing whole-vascular patterned vessels within the structure were adenocarcinoma or adenoma of high-grade atypia, suggesting that this finding seems useful for differentiating cancer from adenoma.