Primary yolk sac tumor of the cerebellar vermis: case report.

A rare case of yolk sac tumor in the cerebellar vermis is reported. A 2-year-old boy developed headaches, vomiting, and an unsteady gait. Later a tumor was demonstrated in the medial part of the cerebellum by gadolinium-enhanced magnetic resonance imaging (MRI). The tumor was totally removed, and the surgery was followed by chemotherapy. Soon after surgery the elevated alphafetoprotein (AFP) levels in the serum and cerebrospinal fluid were observed to decrease to normal levels. Three months later enhanced MRI showed a lesion in the vermis without any elevation of AFP, and the lesion turned out to be a granuloma. Six months after the second surgery a tumor recurred that could not be totally removed. Cranial radiotherapy was given together with chemotherapy, which resulted in a decrease of AFP to the normal range. The patient is doing well without any elevation in AFP at 1 year 6 months after onset. Related problems in the diagnosis and treatment of yolk sac tumors are discussed.