Brachytherapyが有用であった松果体部Germinomaの1例

A Case of Pineal Region Germinoma Treated by Interstitial Brachytherapy

I．はじめに

　一般にgerminomaは放射線感受性が高いことから，全脳あるいは局所照射に加えて症例により全脊髄照射が施行され，この放射線療法のみでも高い奏効率が報告されている^20）．しかし長期生存例の増加とともに，放射線照射による晩期障害が問題となっており^{2,19,21,24）}，その診断と治療については特に患者のuseful lifeの向上という観点から，種々の検討が行われつつある．今回われわれはMRI誘導定位脳手術装置を用い，生検術による組織診断確定の後に放射線組織内照射（brachytherapy）を施行し，良好な結果を得たgerminomaの1例を経験したので，その診断，治療を中心に若干の文献的考察を加え報告する．

Although radiation therapy has been universally accepted as treatment for primary intracranial germino-mas, the optimal technique for both diagnosis and treat-ment continues to be a matter of controversy. We re-port a case of germinoma in the pineal region treated by interstitial brachytherapy. A 23-year-old female was admitted with diplopia and consciousness disturbance.Magnetic resonance imagings (MRI) revealed an en-hanced tumor of the pineal region and hydrocephalus. No serum and CSF tumor markers such as alpha-fetoprotein (AFP), human chorionic gonadotropin (HCG) or placental alkaline phosphatase (PLAP) were detectable. Stereotactic needle biopsy was performed using BRW MRI-guided stereotactic apparatus. After the histological diagnosis confirmed the presence of germinoma, three catheters for interstitial brachyther-apy were implanted into the tumor through the biopsy tract, and iridium-192 seeds were inserted into the catheters and kept there for 5 days to give 35 Gy of irradiation at the tumor periphery. Subsequent MRI showed marked tumor regression and the clinical symp-toms were gradually improved, and Gd-enhanced tumor on MRI completely disappeared 2 months after brachytherapy.

Histological diagnosis is essential before initiation of treatment because a germinoma is commonly thought to be radiosensitive. However, pineal region tumor is dangerous to remove surgically because of high mor-bidity and mortality rates. Image-guided stereotactic technique provides a safe method to obtain an accurate diagnosis, and subsequent interstitial brachytherapy en-ables selective irradiation of the tumor, and does not give rise to complications caused by external irradiation such as mental disturbance, hypopituitarism, visual dis-turbance and brain necrosis. Interstitial brachytherapy following image-guided biospy can be a useful tool for Patients with germinoma.