[Case of rectal carcinoma discovered after extracting a single brain metastasis]

A 79-year-old woman had shown a decline of volition nine months before admission. Because she demonstrated a depressive state, she had been treated with an antidepressant for one month before admission. Thereafter, she became incontinent and showed a poor appetite since two days before admission. Plain computed tomography scan showed an extensive low density area in the right frontal lobe. Cerebral magnetic resonance imaging revealed a tumor with edema (3 cm in diameter), which showed heterogeneous enhancement. The solitary tumor was removed by craniotomy. Metastatic carcinoma was suspected on histological examination, but the primary cancer was not able to be detected by a whole body examination, except for colonoscopy, which was refused by her family. She demonstrated intestinal bleeding about five months after the craniotomy. Rectal cancer was discovered by colonoscopy and she underwent Hartman's procedure. Histological examination revealed poorly differentiated adenocarcinoma similar to resected brain tumor. The final solitary diagnosis was metastatic carcinoma from primary rectal cancer. Solitary brain metastasis from colon cancer is extremely rare, however, we should consider the possibility in cancers of the digestive tract.