Case report and ultrastructural study of intracranial embryonal carcinoma.

A case of a primary intracranial embryonal carcinoma, the first with ultrastructural study, is reported. The tumor was associated with precocious puberty in a 6 1/2-year-old female. Characteristic embryoid bodies were present. At the ultrastructural level three cell types were noted: undifferentiated, differentiated, and intermediate types. The undifferentiated showed scanty cytoplasmic organelles and numerous free polysomes, while the differentiated cells contained well-developed mitochondria, Golgi apparatus, rough endoplasmic reticulum, and some contained secretory granules. The intermediate cells possessed dilated and irregularly-shaped mitochondria but still retained large numbers of free polysomes. The authors suggest that intracranial germ cell tumors be named in conformity with germ cell tumors in other sites, and that terms such as "ectopic pinealoma" and "atypical teratoma of the pineal" be used no longer.