Primary intracranial yolk sac tumor. Immunofluorescent demonstration of alpha‐F etoprotein synthesis

An autopsy case of 20‐year‐old male with primary intracranial yolk sac tumor (endodermal sinus tumor) is reported. Whereas the biopsy specimen obtained from the pineal region showed diffuse proliferation of atypical tumor cells, the metastatic subdural tumor removed from lumbar spinal region had the characteristic histologic appearance of yolk sac tumor. The histologic diagnosis was intracranial yolk sac tumor originating in the pineal gland. The elevated amount of alpha‐fetoprotein in the cerebrospinal fluid and in the serum further supported the diagnosis. At autopsy, only metastatic tumor was present in the posterior fossa. The immunofluorescence study demonstrated the presence of intraand extracellular alpha‐fetoprotein globules in the tumor tissue. The intra‐ and extracellular distribution of alpha‐fetoprotein, in general, appeared to coincide with that of the PAS‐positive hyaline globules in the tumor.