食道原発小細胞型未分化癌の1例

Primary Esophageal Undifferentiated Carcinoma of Small Cell Type, Report of a Case

要旨　患者は48歳，男性．前胸部痛のため近医を受診し，内視鏡検査で中部食道に粘膜下腫瘍様隆起を指摘され，生検で小細胞癌と診断されたため当科を紹介された．X線検査では頂部に淡い不整形のバリウム斑を有する表面平滑な隆起であった．内視鏡検査では表面平滑な0-Isep型の腫瘍で，隆起の大部分はヨードに染色される正常上皮に覆われていたが，立ち上がりは比較的はっきりし丈が高く，頂部には不整な陥凹を伴っていた．さらに隆起辺縁には上皮内伸展様の陥凹も認められた．EUSも含めた検査で深達度sm_2,3と術前診断し外科的切除を行った．病理組織学的には細胞質に乏しい小型の異型細胞の上皮下を主座とした充実胞巣状からシート状の増殖から成りsm深層まで浸潤していた．隆起の立ち上がりから辺縁には0-IIbのm₁扁平上皮癌も併存していた．以上から全腫瘍径20×18mm，0-Isep＋IIb型，小細胞型未分化癌，深達度sm₃，ly₁，v₁，infαと診断した．106recRにリンパ節転移も認められた．術後に化学療法（CDDP＋CPT-11）を追加したがリンパ節再発を来し21か月後に癌死した．

　A 48-year-old man with a complaint of retrosternal pain, was introduced to our hospital with a diagnosis of small cell carcinoma of the middle esophagus. X-ray examination revealed an elevated lesion with smooth margin and irregular barium fleck on the top of the tumor. Endoscopic examination showed a dome-shaped submucosal tumor-like protrusion largely covered with non-neoplastic epithelium and had an eroded central depression (0-Isep). A shallow depression (0-IIc) was also recognized in the adjacent mucosa. Biopsy specimen taken from the central depression was diagnosed as small cell carcinoma (SmCC), and that from peripheral 0-IIc revealed squamous cell carcinoma (SqCC), respectively. EUS revealed a hypoechoic submucosal mass that had expanded into the deeper portion of the submucosal layer. Preoperative CT examination revealed neither lymph node nor distant metastasis. The lesion was diagnosed preoperatively as a primary SmCC of the esophagus, which had invaded as deep as the sm3, without metastases (N0, M0), and the lesion was treated surgically. Gross appearance of the resected specimen showed a whitish submucosal tumor-like protrusion, measuring as much as 17×14 mm in size, with irregular deep ulceration. Histologically, the tumor was mainly situated in the submucosal layer, and was composed of a dense proliferation of small to medium-sized atypical cells with hyperchromatic or granular nuclei and scant cytoplasms arranged in solid nest or sheet-like fashion. Morever, the tumor cells were Grimelius positive, and were immunohistochemically positive for CD56. NSE, and Chromogranin A. SqCC in situ was coexisted separately in the adjacent mucosa. Finally, the tumor was diagnosed histologically as esophageal undifferentiated carcinoma of small cell type, tumor size was 20×18 mm including the concomitant SCC in situ,0-Isep＋IIb, sm3, ly1, v1, infα, n1 (106recR). After surgical resection, the patient was treated with additional adjuvant chemotherapy using CDDP and CPT-11. However,14 months later, mediastinal lymph node metastases appeared, and 21 months later, be died with pleuritis carcinomatosa. It is suggested that the morphological findings of this case showed the typical feature of submucosally invasive SmCC of the esophagus.