未分化型早期胃癌におけるEMRの問題点―病理学的組織学的な立場から

Indication for Endoscopic Mucosal Resection (EMR) of Undifferentiated Type Early Gastric Carcinoma-From a Pathological Viewpoint

要旨　未分化型早期胃癌（m癌316例，sm癌83例）を対象に臨床病理学的検討を行った．リンパ節転移のない未分化型癌の条件は，以下のごとくであった．m癌では，①腫瘍径が15mm以下，②肉眼型が隆起型・平坦型・潰瘍のない陥凹型，③癌が粘膜表層上2/3にとどまり，粘膜筋板が破壊されていない，④癌が粘膜層の下1/3に浸潤しているか粘膜筋板が破壊されているものでも癌の最深部が分化型腺癌．sm癌では，①腫瘍径が15mm以下，②粘膜下浸潤長が300μm以下，③リンパ管侵襲がなく潰瘍・瘢痕のないもの．以上の条件を1つでも満たす症例であった．以上の結果より，主組織型が未分化型癌のEMRの適応は，m癌では，潰瘍あるいは潰瘍瘢痕がない症例．潰瘍・瘢痕があっても，癌浸潤が粘膜表層2/3にとどまっている症例．sm癌では，潰瘍・瘢痕のない症例で粘膜内・粘膜下層ともに純粋な未分化型でリンパ管侵襲がない症例，潰瘍・瘢痕があっても，深達長が300μm以下でリンパ管侵襲のない症例とするのが妥当であると考えられた．

　The risk factor for lymph node metastasis of undifferentiated carcinoma was considered from a pathological viewpoint, using 399 gastric carcinomas of undifferentiated type (316 mucosal and 83 submucosal carcinomas).

　Conditions in which no lymph node metastasis is expected are as follows. In case of mucosal carcinoma, ① tumors less than 15 mm in diameter, ② tumors of polypoid, flat, and depressed type without ulcer, ③ tumors with the invasion limited to the upper 2/3 of the mucosal layer and without destruction of the muscularis mucosae (m.m.), ④ tumors with invasion within the lower 1/3 of the mucosal layer or with destruction of m.m., but whose histological type at the invasive front was differentiated. In case of submucosal carcinoma, ① tumors less than 15 mm in diameter, ② tumors with depth limited to 300μm from the m.m., ③ tumors with neither ulcer nor lymphatic permeation. Therefore, the indications for EMR of undifferentiated carcinoma are as follows. In case of mucosal carcinoma, ① tumors without ulcer, ② tumors with invasion limited to the upper 2/3 of the mucosal layer. In case of submucosal carcinoma, ① tumors whose histological type of mucosal and submucosal component are purely undifferentiated, with neither ulcer nor lymphatic permeation, ② tumors with invasion depth limited to 3001μm from the m.m. and without lymphatic permeation.