Primitive neuroectodermal tumor (PNET). A case report.

The authors present a case of relatively rare tumor of the central nervous system (CNS) in a 19-year-old female, who died 18 months after the first manifestation of meningismus, increased intracranial pressure and secondary hydrocephalus. Brain autopsy revealed abundant neoplastic infiltrations, which spread through the subarachnoid space. Neoplastic infiltrations were also present in the third ventricle and in a form of small subependymal nodules along the whole ventricular system. The microscopical examination showed that neoplasm consisted of small cells, which formed neuroblastic Homer Wright rosettes. Immunohistochemical studies (for synaptophysin, chromogranin A, GFAP, vimentin) together with morphology and localization of neoplasm suggested diagnosis of primitive neuroectodermal tumor (PNET) that spread mainly in the leptomeninges and caused obliteration of subarachnoid space.