Primary diffuse leptomeningeal gliomatosis (PDLG): a neoplastic cause of chronic meningitis.

Cancerous 'chronic meningitis' may be related to subarachnoid space involvement by solid tumors, hematologic malignancies or rarely intraparenchymatous gliomas. Primary leptomeningeal gliomatosis is a rare condition that is attributed to malignant transformation of heterotopic neuroglial tissue. We discuss the clinical and biological features of a patient who died with the diffuse form of primary leptomeningeal gliomatosis (PDLG). A literature search shows that a one to two months long non-specific prodromal phase followed by a fluctuating neurologic downhill course is suggestive of this disease. Cerebro-spinal fluid (CSF) cytology has been diagnostic in only 1 of 8 reported cases. Recent technical progress, including the use of GFAP (glial fibrillary acidic protein) directed antibody, may enhance the sensitivity of CSF cytologies. Diagnosis may require repeated cerebral biopsies, because the hemispheric lesions are often separated by normal tissue. PDLG must be added to the large differential diagnosis of 'chronic meningitis'.