Primary medulla oblongata germinoma--an unusual posterior fossa tumors in young adults.

We encountered 2 patients with germinoma arising from the medulla oblongata in whom preoperative radiological diagnosis was difficult. A 30-year-old woman presented due to aspiration pneumonia caused by bilateral lower cranial nerve palsies, and a 24-year-old man presented with headache caused by obstructive hydrocephalus. In both patients, there was a midline tumor that extended from the lower part of the fourth ventricle to the C1 lamina level. It was well-demarcated and homogeneously enhanced tumor with a slightly high density on plain CT scan. The preoperative diagnosis for both patients was ependymoma. The former patient had persistent lower cranial nerve palsies due to brain stem injury after tumor resection. Both patients achieved complete remission with adjuvant therapy. Fewer than 10 cases of germinoma affecting the medulla oblongata have been reported. Radiological findings resembling those of the pineal region germinoma were observed in the two patients reported here. We would like to stress the importance of remembering germinoma when making a preoperative differential diagnosis of fourth ventricular tumors in young adults.