興味ある形態を呈した盲腸結節集簇様病変の1例

Nodule-Aggregating Tumor of the Cecum, Report of a Case

要旨　患者は67歳，男性．スクリーニングを目的に施行した大腸内視鏡検査で盲腸に大きさ40mmの結節集簇様病変を認めた．病変は比較的小型で均一な丈の低い結節により形成されていたが，中央部に発赤調で類円形を呈するIIa+IIc様の部分を認めた．発赤部分のpitは消失し無構造を呈しており，粘膜下層以深へ浸潤した癌が疑われ，周辺の結節部分についてはその性状から腺腫の可能性が高いと考えられた．注腸X線検査では，病変は大きさ40mmの結節の集簇として抽出され，中央に大きさ15mmの類円形の浅い陥凹を認めた．細径超音波プローブ所見を加味し，病変は中央部分で粘膜下層にmassiveに浸潤した癌と診断し，腹腔鏡下回盲部切除術を施行した．病理組織学的には，病変は中央の陥凹部分で深達度sm₃まで浸潤した中分化腺癌であり，周辺の結節部分は中等度異型腺腫であった．病変の形態，発育進展において興味ある症例と思われ報告した．

　The patient was a 67-year-old man. Colonoscopy at screening revealed a nodule-aggregating tumor, 40 mm in size at the cecum. The lesion consisted of relatively small homogeneous nodules and a reddish depressed area of 15 mm diameter was seen at the center. From colonoscopic observations it was obvious that the depressed portion at the center was devoid of pits and no longer maintained its structure and thus the lesion was thought to be cancer infiltrating deeply into the submucosa. Furthermore the surrounding nodules were thought to be adenoma. On barium enema radiograph the lesion was revealed as a 40 mm-large mass of nodules with a shallow roundish depression, 15 mm in size, at the center. From comprehensive analysis of the images including ultrasonographic findings the lesion was diagnosed as a cancer with massive infiltration into submucosa at the center. Laparoscopy-assisted ileocecotomy was performed. Histopathologically the central depression was composed of moderately differentiated adenocarcinoma with an infiltration depth at sm3 and the surrounding nodular portion was composed of tubular adenoma with moderate atypia.