他臓器癌の直接浸潤による転移性大腸癌の2例

Two Cases of Metastatic Colorectal Cancer which had Arisen Directly from Other Organs

要旨　〔症例1〕は80歳，男性．前立腺癌の治療中に施行したMRI検査にて直腸癌を疑われ，下部消化管内視鏡検査を施行した．直腸前壁に発赤調の粗糙な顆粒状隆起病変を認め，前立腺癌の転移と診断された．治療を継続したが，半年後の内視鏡検査では，腫瘍は全周性に進展しびまん型を呈していた．〔症例2〕は71歳，男性．便潜血陽性のため下部消化管内視鏡検査を施行した．遠位横行結腸から近位下行結腸にかけて，大小の一部発赤調の粘膜下腫瘍様隆起を散見した．腹部CT検査および生検にて腎細胞癌の転移と診断した．以上，大腸低分化腺癌との鑑別を要した転移性大腸癌2例を報告した．

　Metastatic colorectal cancer is a rare disease, and in quite a few cases the differential diagnosis from primary colorectal cancer is difficult. We report our experience with two cases of metastatic colorectal cancer. The patient in Case 1 was an 80-year-old man who was suspected of having rectal cancer based on an MRI examination performed during treatment for prostatic cancer and was examined by lower gastrointestinal endoscopy. A reddish, coarse, granular protrusion was observed on the anterior wall of the rectum, and it was diagnosed as a metastasis of the prostatic cancer. Treatment was continued, but an endoscopic examination 6 months later showed that the tumor had spread around the entire circumference and was the diffuse type. The patient in Case 2 was a 71-year-old man who was examined by lower gastrointestinal endoscopy after of a positive fecal occult blood test. Scattered reddish submucosal tumor-like protrusions of various sizes were observed from the distal transverse colon to the proximal descending colon. Metastasis by renal cell carcinoma was diagnosed on the basis of abdominal CT and biopsy findings, and the patient was treated surgically. Metastatic colorectal cancers exhibit a variety of morphological forms, and the diagnosis needs to be made through an overall evaluation of the imaging findings, such as the CT and MRI findings, in addition to lower bowel contrast radiography and endoscopy findings.