類骨形成を伴った食道の"いわゆる癌肉腫"の1例

So-called Carcinosarcoma of the Esophagus with Foci of Osteoid Formation, Report of a Case

要旨　患者は47歳，男性．貧血の原因検索中に食道に異常を指摘され，当科に紹介された．X線・内視鏡検査で胸部中部食道に2cm大のpolypoid lesionが認められ，周囲に全周性のⅡc病巣を伴っていた．生検では扁平上皮癌と紡錘形細胞の両方が採取された．EUSで深達度sm3と診断し，右開胸による3領域郭清を行った．組織学的には扁平上皮癌と，錯綜する紡錘形細胞肉腫との問に移行像が認められ，肉腫様成分内に一部類骨の形成が認められた．免疫染色では扁平上皮癌部分はkeratin陽性，肉腫様部分はvimentin陽性であった．類骨の部分は両方陰性で，骨芽細胞の配列はなく，周辺部より類骨中に異型細胞が見られ，腫瘍細胞によって形成された類骨と判断し，類骨の形成を伴う“いわゆる癌肉腫”と診断した．深達度sm3，n0 であった．癌肉腫の本邦報告例は検索しえた限りでは140例あり，若干の文献的考察を行った．

　A 47-year-old asymptomatic male was admitted to our department for more detaled medical evaluation and treatment of a polypoid lesion in the esophagus. X-ray and endoscopic examination revealed a polypoid lesion, 2.0 cm in diameter, in the middle thoracic esophagus. A reddish and slightly depressed Ⅱc lesion was noticed around this tumor. Squamous cell carcinoma and spindle-shaped cells were found in the endoscopic biopsy specimens. Endoscopic ultrasonography disclosed sm3 invasion. Thoracic esophagectomy with right thoracotomy and neck dissection was performed. Microscopic examination of the resected specimens revealed that the tumor consisted of Squamous cell carcinoma and spindleshaped sarcomatous elements. The transitional feature was observed in these two components, and osteoid formation was seen in the sarcomatous portion. Immunohistochemical examination disclosed keratin-positive cells in the carcinomatous area and vimentin-positive cells in the sarcomatous element. But neither keratin-positive nor vimentin-positive cells were found in the osteoid tissue. This tumor was diagnosed as so-called carcinosarcoma with foci of osteoid formation. The depth of tumor invasion was sm3, and no metastasis was found in the resected lymph nodes. One hundred and forty cases of carcinosarcoma of the esophagus have been reported in Japan, and discuss the relationship and histogenesis of these tumors.