前頭葉転移性甲状腺腫の1例

METASTATIC STRUMA IN THE FRONTAL LOBE : REPORT OF A CASE

Ｉ．はじめに

　原発巣不明の悪性腫瘍脳内転移例は，われわれ脳外科医がときどき経験するところであり，その大多数が肺癌を原発とするものである^1）。今回われわれは前頭葉腫瘍摘出後それが甲状腺乳頭状腺癌と判明，そのさい原発巣はまつたくみいだしえず，7カ月後初めて小豆大の原発巣を甲状腺に発見，これを手術によつて切除した1症例を経験したので報告する。

A brain tumor located in the frontal lobe was extirpated and histologically proved to be metastasis of the thyroid tumor. But the primary site of the tumor in the thyroid was not clinically detected. After 7 months of follow up, a small carcinoma was found in the thyroid and resected.

The patient was 33-year-old housewife. She suf-fered from failing vision for three months prior to admission. Bilateral choked disks were noticed. The physical examination was negative. Carotid angio-graphy revealed a tumor in the right frontal lobe. Craniotomy was performed, and a cystic tumor, con-taining 50 cc of colloidal fluid, was extirpated. Histo-logically, colloid-producing follicular structures with papillary pattern were noted along the wall of the cyst, and diagnosed papillary adenocarcinoma of low malignancy of thyroid origin. The colloidal fluid in the cyst contained 110γ/dl of PBI, of which 9.6% was organic iodine. The tumor was biochemically an abnormal thyroid tissue with less differentiated function. Nothing abnormal was noticed in her cer-vical region. I¹³¹-scintigram appeared normal, and no abnormal uptake of I¹³¹ was found in the head and chest. She discharged a month after operation and followed up. Seven months after craniotomy, repeated I¹³¹-scintigram of the thyroid revealed a cold area in the left lobe. A small nodule, measuring 5 mm in diameter, was discovered in the left lobe of the thyroid with a minute metastasis in the ad-jacent lymph node. Left radical lobectomy was per-formed. Histologically, the nodule in the thyroid was papillary adenocarcinoma, less differentiated than the metastatic frontal lobe tumor, and considered as the primary lesion.