[Expanding mature pineal teratoma syndrome. Case report].

We present a case of growing teratoma syndrome of the pineal region. To our knowledge, this is the fourth case reported in the literature. A 13-year-old boy was referred for intracranial hypertension and bilateral papillary edema. CT scan showed a pineal region tumor with obstructive hydrocephalus. After CSF (cerebrospinal fluid) shunting, MRI showed that the tumor had a heterogenous signal enhancement. The tumor marker HCG (human chorionic gonadotrophin) was elevated in CSF and serum. After three cycles of chemotherapy, MRI showed an important increase in tumor size with morphologic modifications. However, HCG in CSF and serum returned to normal. Surgical resection was performed and histological examination of the whole specimen showed mature teratoma. On postoperative MRI, there was a small area of signal enhancement of the left thalamus. Radiotherapy was given. The child was in complete remission 15 months after the diagnosis. Growing teratoma syndrome is a mixed germ cell tumor with a secreting portion that responds to chemotherapy and a non secreting portion of mature teratoma that continues to grow under chemotherapy. The treatment should include chemotherapy for the malignant secreting portion and surgery for the mature teratoma.