食道小扁平上皮癌の深達度診断―内視鏡診断

Endoscopic Estimation of Depth of Invasion in Cases with Small and Minute Squamous Cell Carcinoma of the Esophagus

要旨　2005年1月～2009年6月までに内視鏡治療を行った食道表在癌417例中，小癌は54例56病変（13％），微小癌は34例37病変（8％）であった．（1）微小癌34例37病変の病型は，0-IIa 4病変（11％），0-IIb 13病変（35％），0-IIc 19病変（51％），0-I 1病変（3％）であり，0-IIbと0-IIc病変で86％を占めていた．深達度では，35病変（95％）がT1a-EP癌であり，T1a-LPM癌とT1a-MM癌が各1病変のみであった．T1a-LPM癌の1病変は0-IIc，T1a-MM癌の1病変は0-Iであった．（2）小癌54例56病変の病型は，0-IIa 3病変（5％），0-IIb 14病変（25％），0-IIc 38病変（68％），0-I 1病変（2％）であり，0-IIbと0-IIc病変で93％を占め，なかでも0-IIc型が多く約70％を占めていた．深達度では，T1a-EP癌41病変（73％），T1a-LPM癌3病変（6％），T1a-MM癌8病変（14％），SM2以深癌が4病変（7％）であり，T1a-EPとT1a-LPM癌が約80％を占めていたが，残り20％はT1a-MM癌とSM2以深癌であった．T1a-MM癌，SM2以深癌12病変中，11病変は0-IIc，残り1病変はSM2の0-Iであった．T1a-MM癌2病変とSM2以深癌2病変の計4病変では脈管侵襲陽性であった．微小癌と小癌の深達度診断は，病変の61％を占める0-IIcの深達度診断が主であり，通常観察では，陥凹の程度，陥凹底の色調，陥凹内の凹凸の有無，陥凹周囲の盛り上がりの有無が，NBI併用の拡大観察では，微細血管の変化が壁深達度診断の指標となる．

　In order to find clinical and pathological features of small squamous cell carcinomas of the esophagus,88 cases with 93 small cancer lesions were analyzed in this study. They occupied 18.2％ of 417 cases with superficial and squamous cell carcinoma of the esophagus that underwent endoscopic resection from January 2005 to June 2009.

　Results:（1）54 cases（13％ of all cases）had 56 small cancer lesions less than 10mm in size and 34 cases（8％）had 37 minute cancer lesion less than 5mm.（2）In cases with minute cancers（37）, 4 lesions（11％）could be classified into type 0-IIa, 13 lesions（35％）type 0-IIb, 19 lesions（51％）type 0-IIc and 1 lesion（3％）type 0-I. Type 0-IIb and type 0-IIc lesions occupied 86％ of all minute squamous cell carcinoma lesions. Pathological studies on resected specimens revealed that 35 lesions（95％ of all minute cancer lesions）remained in the epithelium（EP）, one lesion（2.5％）infiltrated into the lamina propria mucosae（LPM）and also another one lesion（2.5％）reached to the muscularis mucosae（MM）. One minute LPM cancer was a type 0-IIc lesion and another MM lesion was type 0-I.（3）In cases with small cancers（56）, 3 lesions（5％ of all lesions）were type 0-IIa, 14（25％）0-IIb, 38 lesions（68％）type 0-IIc and one（2％）type 0-I. Type 0-IIb and 0-IIc lesions occupied 93％ of all minute cancer lesions. Fourty one lesions（73％ of all small cancer lesions）were EP cancers, 3 lesions（6％）LPM, 8（14％）MM and 4（7％）invaded moderately into the submucosa（SM2）. EP and LPM cancer lesions occupied 80％ of all small cancers while residual 20％ included lesions with deeper invasion into MM and SM2. All eight lesions with MM invasion were type 0-IIc cancers, three of four SM2 cancers were also type 0-IIc and one lesion was type 0-I lesion. Microvascular permeation was noted in 2 among 8 MM cancers（25％）and 2 among 4 SM2 cancers（50％）, suggesting probable lymph node metastasis.（4）EP and LPM cancers occupied 86％ of all small and minute cancers and MM and SM 14％. Endoscopic differentiation of type 0-IIc lesions with deeper invasion is most important in endoscopy, for type 0-IIc occupied 85％ of all small and minute cancers with MM or SM invasion. Partial and deeper depression, partial and dark reddening, granular irregularities in the depressed area and marginal elevation of type 0-IIc lesions strongly suggested deeper invasion at conventional endoscopy. Abnormalities in IPCL by NBI observation are suggestive of deeper invasion.

　Conclusions:（1）Type 0-IIb and 0-IIc lesions occupied 90％（IIb : 29％ and IIc : 61％）of all small and minute cancers. （2）EP and LPM cancers occupied 86％ of all small and minute cancers. （3）Differentiation of type 0-IIc cancers with MM and SM invasion is point of endoscopic diagnosis on small and minute squamous cell carcinoma of the esophagus, for type 0-IIc lesions occupied 85％ of all MM and SM cancers.