[A case of pineal region germinoma treated by interstitial brachytherapy]

Although radiation therapy has been universally accepted as treatment for primary intracranial germinomas, the optimal technique for both diagnosis and treatment continues to be a matter of controversy. We report 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 enhanced 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 brachytherapy 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 symptoms 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 morbidity and mortality rates. Image-guided stereotactic technique provides a safe method to obtain an accurate diagnosis, and subsequent interstitial brachytherapy enables selective irradiation of the tumor, and does not give rise to complications caused by external irradiation such as mental disturbance, hypopituitarism, visual disturbance and brain necrosis. Interstitial brachytherapy following image-guided biopsy can be a useful tool for patients with germinoma.