脳実質内転移を示した大腸癌の2例—症例報告と文献的考察

TWO CASES OF THE BRAIN METASTASIS FROM THE CANCER OF COLON : CASE REPORTS AND LITERATURE REVIEW

I．はじめに

　大腸癌が脳実質内へ移転することは肺癌，乳癌などの場合に比べ比較的稀である。

　著者らは最近臨床的に脳転移が疑われ，手術により組織学的にこれを確めることのできた大腸癌の2例を経験した。本稿では症例を報告するとともに，大腸癌の脳転移に関する文献的考察ならびに臨床症候の解析・検討（特に1例の運動失調を中心に）を行う。

Two unusual cases of the brain metastasis from the the cancer of colon were reported.

A 63 year old female (case 1), who received hemicolectomy for carcinoma of the transeverse colon about a year ago, was admitted because of progressive unsteady gait, nausea and vomiting. She disclosed marked trunkal ataxia, right limb ataxia, right Homer sign, right facial palsy and bilateral horizontal gaze nystagmus. Computed to-mogram revealed low density area (4×5cm) in the posterior fossa. Following the infusion of contrast material a scattered enhancement was noted within this low density area. Surgical removal was total-ly done and the pathological diagnosis of the tumor was adenocarcinoma, consistent with a primary colon carcinoma.

A 52 year old male (case 2) had generalized con-vulsion and then walked unsteadily. Four months ago, he had low anterior resection of carcinoma of the sigmoid colon. On examination, he showed mild dysarthria, left facial palsy and left limb ataxia. Computed tomogram revealed a mild increased density (5cm in size) with surrounding edema in the right frontal region. After infusion of contrast material there was marked enhancement of a mass lesion. On neurotological examination, persuit move-ment was saccadic, especially on right direction, optokinetic nystagmus was suppressed in left side and visual suppression of caloric nystagmus was disappeared in both directions. However, after removal of the mass these abnormal findings were all improved. Surgery (subtotal removal) revealed metastatic adenocarcinoma, compatible with a pri-mary carcinoma. We postulated that his ataxia was attributed to frontal ataxia and discussed from a neurotological point of view.

Carcinoma of the large intestine relatively rarely metastasize to the brain, possibly because of the filtering effct of the pulmonary and hepatic circu-lation.