[Primary endodermal sinus tumor of the fourth ventricle (author's transl)].

A case, a 18-year-old male, of an endodermal sinus tumor (yolk sac tumor) in the fourth ventricle, was reported. The patient had a month history of headache, vomiting and gait disturbance prior to the hospitalization, when he admitted to our service he was in lethargic condition with left cerebellar ataxia and horizontal nystagmus. Lumbar tap revealed clear CSF under normal pressure of 110 mm H2O with the CSF protein of 432.5 mg/dl and cell count of 147/3. The vertebral angiography demonstrated space occupying lesion in the posterior fossa. Plain CT demonstrated only disappearance of the fourth ventricle and slightly dilated bilateral ventricles and third ventricle. However diffuse high density area around the fourth ventricle was demonstrated and the wall of bilateral anterior horn was slightly enhanced, after injection of contrast media. There was no other abnormal findings around the pineal region. Suboccipital craniectomy was performed and the tumor was totally removed macroscopically. The tumor was situated in th floor of the fourth ventricle and infiltrated into the fourth ventricular wall and th adjacent cerebellar tissue. The tumor was with soft, greyish color and extremely vascular. Histologically the tumor was diagnosed as endodermal sinus tumor according to Teilum's classification. There were stellate cells arranged in a loose with vacuolated network which formed cystic cavities and a complicated network of honeycomb appearance with a system of communicating cavities and channels. Various size of intra- and extracellular PAS-positive hyaline globules were also seen. Glomerular-like structure (Schiller-Duval body) was not observed. Immunoperoxidase study clearly demonstrated the presence of intra- and extracytoplasmic alpha-fetoprotein granules in the tumor tissue. The amount of the serum alpha-fetoprotein, measured by radioimmunoassay, showed 400 ng/ml. After irradiation in the posterior fossa (5000 rad) the patient was discharged. Three months later, follow up CT demonstrated small high density area in the anterior horn of the left lateral ventricle, so he was rehospitalised. Irradiation in the whole brain was again administered. The tumor was very radiosensitive. CT, after 800 rad, demonstrated complete disappearance of the tumor. After irradiation totally (3000 rad), he discharged with left cerebellar ataxia.