中・下咽頭表在癌の内視鏡診断―通常内視鏡およびNBIの立場から

Endoscopic Diagnosis of Meso and Hypo-pharyngeal Carcinoma in Early Stage

要旨　自験中・下咽頭表在癌内視鏡治療例は63例84病変であり，全例男性，平均年齢68歳であった．63例中59例（93.7％）は食道癌の合併あるいは治療後，2例は頭頸部癌の治療後，1例は胃癌術後であり，癌の既往がなかったのは1例のみであった．多発病変が多く，同時性多発が15例（24％），異時性多発が9例（14％）であった．全例，上部消化管内視鏡検査で発見しており，最初の白色光観察で64病変（76％），NBI観察で13病変（16％），通常・NBIでは不明で，別病変治療時のヨード染色による発見が7病変（8％）であった．ヨード染色による発見例は，大きさ3～12mm，86％が0-IIb病変であった．存在部位は，中咽頭15病変（18％），下咽頭69病変（82％）であり，右梨状陥凹の病変が最も多く25％を占めていた．病変の大きさは3～40mmであり，内視鏡病型は，0-I 5病変（6％），0-IIa 36病変（43％），0-IIa＋IIc 4病変（5％），0-IIb 26病変（31％），0-IIc 11病変（13％），0-IIc＋IIa 1病変（1％），2型類似1病変（1％）と，隆起性病変が半数を占めていた．上皮内癌が68病変（81％），上皮下浸潤癌が16病変（19％）であり，上皮下浸潤癌のうち上皮下に広く深く浸潤した0-I型2例と2型類似1例の計3例（19％）は脈管侵襲陽性であった．深達度別に内視鏡病型を考えると，平坦な0-IIb，表面に凹凸を伴わない0-IIa，周囲に盛り上がりを伴わない0-IIcは上皮内癌であり，丈が高く，基部の広い0-I，0-IIa＋IIcなどの混合型，辺縁隆起や陥凹内隆起を伴う0-IIcは，上皮下浸潤癌の可能性が高いと言える．

　Recent development of upper GI endoscopy allowed us to find pharyngeal cancer in early stage. Studies on clinico-pathological characteristics of them probably promote endoscopic early detection of pharyngeal cancer.

　In order to know endoscopic and pathological characteristics of pharyngeal cancer in early stage, patients with superficial pharyngeal cancer treated by EMR（endoscopic mucosal resection）were studied.

　63 patients with 84 superficial cancer lesions in the pharynx were studied. All of them underwent Upper GI endoscopy and superficial cancer lesions were detected and treated by EMR. All of them were male and 68 year-old in average. Malignant lesions in other organ than pharynx were frequently 98.4％（esophagus 93.6％, head and neck 3％ and stomach 1.6％）. All pharyngeal lesions were detected by UGI endoscopy（by white light observation 76％, by NBI（narrow band imaging）16％ and by iodine staining 8％）. Type IIb cancer（flat lesion）occupied 86％ of all lesions identified only by iodine staining while conventional white light or NBI observation failed. Macroscopic characteristics of superficial pharyngeal cancers were as follows. （1） multiple cancers were frequent（39％ : synchronous 24％ and metachronous 14％）. （2） Hypopharyngeal cancers were most frequent（82％）while mesopharyngeal cancers in 18％ of all cases. （3） Elevated type occupied 54％ of all cases（0-I 6％, 0-IIa 43％, 0-IIa＋IIc 5％）, while flat type（type 0-IIb）31％ and slightly depressed type（type 0-IIc）13％. （4） Pathological studies on resected specimens revealed that the depth of cancer invasion was confined to the epithelium in 81％ of all lesions and reaching to the subepithelial layer 19％ including 3 cases（19％ : 2 cases with type 0-I lesions that had wide subepithelial invasion and 1 type 2 lesion）with micro-vascular permeation suggesting probability of metastasis.

　Considering those facts, cancer invasion probably be confined to the epithelium when cancer lesions showed flat type（type 0-IIb）, slightly elevated type（type 0-IIa）with smooth surface and slightly depressed type（type 0-IIc）without slight elevation close to the cancer lesion. On the other hand, subepithelial invasion should be suspected when a type 0-I lesion was tall and had wide base, a type 0-IIc lesion had irregular surface or slight elevation close to the depression, and combined type such as type 0-IIa＋IIc.