Neuroepithelial and ectomesenchymal differentiation in a primitive pineal tumor ("pineal anlage tumor").

A primitive tumor of the pineal region in a 9-year-old girl led to death after 5 months of increased intracranial pressure with occlusive hydrocephalus. Histological investigation including immunocytochemistry revealed a broad spectrum of neuroectodermal differentiation with neuroblastic, neuronal, ependymal and retinoblastomatous features. Melanotic epithelial formations were similar to those of the so-called retinal anlage tumor and of the developing pineal gland. Striated muscle fibers indicated additional ectomesenchymal differentiation reminiscent of the close topographical relationship between neural crest and neural tube on the prosencephalic level of the pineal anlage. This developmental situation seems to be neoplastically reflected by the differentiation features of this tumor.