多発大腸微小カルチノイドを有する家族性大腸腺腫症の1例

Familial Adenomatosis Coli Associated with Multiple Microcarcinoids in the Colon and Rectum, Report of a Case

要旨　26歳男性，左下腹部の痛みと腫瘤，粘血便を主訴として受診．家族性大腸腺腫症に伴う大腸癌と診断され，大腸亜全摘を受けたが，術後8カ月で同癌の肝転移のために死亡．大腸の全割標本で，無数の腺腫，16個の腺癌，168個の内分泌細胞微小胞巣の巣状集団が確認された．同集団は，直腸～S状結腸に多く分布し，腺腫の深部にみられることが多かった．同集団は1～38個の同胞巣から成り，大きさは12～1,050μmで，あるものは粘膜下層へ浸潤していた．同胞巣はすべて好銀性細胞で構成され，電顕的に径140nmの円形顆粒を有する内分泌細胞（D₁細胞）の均一集団で形成されていた．以上の特徴を有する内分泌細胞微小胞巣の巣状集団は，通常の大腸疾患にみられず，家族性大腸腺腫症に随伴する微小カルチノイドおよびカルチノイドの芽と考えられる．

　The patient, a 26 year-old man, was admitted with chief complaints of pain and a tumor in the left lower abdomen and mucous-bloody stool. In his family history, his older brother died of colon cancer associated with familial adenomatosis coli.

　With the gastrointestinal series and biopsy he was also diagnosed as having colon cancer associated with familial adenomatosis coli. Subtotal colectomy with ileorectal anastomosis was done. Eight months after the operation he died of metastatic liver cancer.

　Histological examination on the surgically resected specimen revealed numerous adenomas, 16 adenocarcinomas and 168 clusters of endocrine-cell micronests in the colon and rectum. The clusters were characteristically found chiefly in the rectum to sigmoid colon and they were localized under the adenomas. They measured 12 to 1,050 μm (average size: 205 μm), were mainly limited to the deep lamina propria mucosae and occasionally infiltrated into the muscularis mucosa and submucosa. They were homogeneously composed of non-argentaffin, argyrophil endocrine cells uniformly containing round secretory granules, 140 nm in size (D₁ cell type granules).

　Ordinary colonic disorders have never associated with such lesions. Because the clusters ultrastructurally consisted of the same kind of endocrine cells as that of ordinary rectal carcinoids, and moreover they showed a proliferative and infiltrative behavior, the clusters were considered as microcarcinoids.

　This is the first report of familial adenomatosis coli associated with multiple microcarcinoids in the colon and rectum.