Primary yolk sac tumor of bilateral basal ganglia.

A primary intracranial yolk sac tumor (YST) is a type of germ cell tumor (GCT) and usually involves the pineal or suprasellar regions, as do other GCTs. Primary YST in the basal ganglia is not common, and bilateral basal ganglia involvement is even rarer. Early diagnosis is often difficult because of minimal or subtle findings without space-occupying lesions shown on neuroimaging during the early course of the disease. We report a case of primary intracranial YST encountered in the basal ganglia bilaterally and describe the clinical presentation, diagnostic problem, imaging characteristics, histopathologic features, and prognosis of the tumor. To the best of our knowledge, this is only the third reported case of primary YST confined to the basal ganglia in the literature.