隆起型食道扁平上皮癌の深達度診断―拡大内視鏡を中心に

The Diagnostic Accuracy of the Japan Esophageal Society Classification for Superficial Esophageal Squamous Cell Carcinoma

要旨　日本食道学会から食道扁平上皮癌の拡大内視鏡分類（日本食道学会分類）が提唱されたが，隆起型病変に対する診断精度は不明である．対象と方法：当院でESDを施行した隆起型扁平上皮癌40病変を対象とし，日本食道学会分類診断と病理組織像との相関を検討した．結果：正診は，Type B1が18病変中14病変，Type B2が13病変中4病変，Type B3が1病変中1病変であり，正診率は48％（40病変中19病変）であった．考察：誤診した原因は，（1）角化やびらんにより血管が視認不可能，（2）表層をEP～LPM癌に被覆された浸潤癌，（3）Type B2の深読みおよび浅読みの3つに大別された．（1）および（2）は通常観察での所見を，（3）はType B2領域のサイズおよび色調を加味することで，その大部分を正診することが可能であった．結語：日本食道学会拡大内視鏡分類に通常観察を加味することで，隆起型病変の深達度診断は向上すると考えられた．

　A new classification of magnified endoscopic findings for esophageal squamous cell carcinoma was developed by the JES（Japan esophageal society）classification. It is a simple classification, and widely accepted. However, its usefulness for the diagnosis of invasion depth of protuberant lesions was unknown.

　Patients and method : 40 protuberant esophageal SCC〔squamous cell carcinoma（0-I or 0-IIa）〕from 351 esophageal SCC treated by ESD（endoscopic submucosal dissection）in Saku Central Hospital from November 2008 to Oct 2012 were enrolled in this study. Invasion depth was classified into three groups ; Ep-LPM, MM-SM1 and SM2 according to the Japanese classification. The invasion depth was diagnosed as EP-LPM, MM-SM1 and SM2 based on the JES classification B1, B2 and B3.

　Result : 14 of 18, 4 of 13 and 1 of 1 in the B1, B2 and B3 group were diagnosed correctly. Therefore, the accuracy was 48％.

　Discussion : There were 3 major factors for misdiagnosis. The first was difficulty of observation. The vascular pattern was not able to be observed in 8 of 40 lesions, because of hyperkeratinization or erosion. However, the invasion depth of such lesions could be diagnosed correctly by WL（white light）endoscopy. The second factor was a unique invasion pattern（submucosal tumor-like invasion）. Sometimes the invaded SCC was covered by EP-LPM SCC, and the surface vascular pattern was B1 in such cases. However, the lesion was able to be diagnosed as submucosal invaded SCC from submucosal tumor-like findings by WL endoscopy. The final factor was low accuracy in B2. seven and 2 cases of 14 was Ep-LPM and SM2. However, the invasion depth has a relationship with the size of B2 area and color of the lesion. The invasion depth was EP-LPM and SM2, when the size of B2 area was 2 mm or less and 4mm or more. And the white lesion was Ep-LPM. Therefore, a combination between WL and magnified endoscopic findings may improve the accuracy.