原発巣に骨形成を認めた大腸癌の1例

Adenocarcinoma of the Colon with Ossification, Report of a Case

要旨　患者は61歳，男性．1年前から便秘気味で，4か月前より排便障害が強くなり，左下腹部痛が出現したため，当科外来を受診した．初診時に左下腹部に一致して5×4cmの硬くわずかに可動性のある腫瘤を触知した．腫瘍マーカーに著変はなかったが，注腸透視，腹部CT検査，大腸内視鏡，下腸間膜動脈造影など，各検査所見から下行結腸癌と診断し，左半結腸切除術を施行した．腫瘍は5.0×5.5×5.2cmの腫瘤型（Borrmann 1型）で，組織学的には中分化腺癌で，間質に明らかな骨形成を認め，骨周囲および骨内に造骨細胞および破骨細胞を認めた．大腸癌の原発巣に骨化を伴った比較的まれな症例を経験したので報告した．

　A 61-year-old man, who had suffered from constipation for a year, visited Gunma University Hospital because of abdominal pain and a defecation disorder which had continued for four months. There was a hard and slightly mobile tumor (5×4cm in size) in the left lower abdomen at the seat of the abdominal pain. Tumor markers were within normal limits. An invaginated mass was recognized by barium enema (Fig. 1), and computed tomography showed an unhomogenous high density area, 5×6cm in size at the lesion (Fig. 2). A tumor, Borrmann type 1, was demonstrated by colonofiberscopy in the descending colon 45cm from the anal verge. Tumor stain and stretching of the vasa recta were demonstrated by inferior mesenteric arteriography (Fig. 3). Left hemicolectomy was done following a diagnosis of descending colon cancer. The stage of the lesion was advanced with lymph node metastasis and serosal invasion (N₁ S₂ P₀ H₀). Histologically, the tumor showed moderately differentiated adenocarcinoma with ossification throughout the interstitial tissue (Figs. 6 and 7). We have reported this case because colon cancer with ossification is very rare.