NEOPLASTIC MENINGITIS AS THE PRESENTATION OF OCCULT PRIMITIVE NEUROECTODERMAL TUMORS

Seven children and young adults initially presented with subacute meni ngitis and/or increased intracranial pressure. The diagnosis of neopla stic meningitis secondary to a primitive neuroectodermal neoplasm was delayed by the absence of an obvious primary tumor. The neuroradiologi c appearance was that of a basimeningeal infiltrative process, complic ated by communicating hydrocephalus or ''pseudotumor cerebri.'' Myelog raphy was important in the diagnosis of disseminated meningeal maligna ncy in four cases. Cerebrospinal fluid cytologic diagnosis was insensi tive but ultimately confirmed in five cases. All seven patients experi enced progressive disease despite neuraxis radiotherapy and intensive chemotherapy; six have died. Systemic dissemination to bone and/or per itoneum occurred in three patients while on therapy. In two, a primary parenchymal brain or spinal cord tumor could not be identified at pos tmortem examination. The presentation of a primitive neuroectodermal t umor as subacute meningitis without an evident primary tumor heralds a n aggressive and refractory neoplasm.