Leptomeningeal infiltration as the presenting manifestation of a malignant glioma.

Infiltration of the leptomeninges by a malignant glioma typically occurs with recurrent supratentorial tumors, but patients may present with leptomeningeal gliomatosis before the primary tumor is diagnosed. This report describes two patients who presented with headache and signs of multifocal neurological disease. One of the patients had neurofibromatosis type I. In both patients the cerebrospinal fluid examination showed a mild pleocytosis, but malignant cells were not detected. The diagnosis of leptomeningeal gliomatosis was not confirmed until autopsy, but in retrospect imaging showed a small, asymptomatic primary tumor in both patients. Leptomeningeal gliomatosis should be considered in the differential diagnosis of chronic meningitis, if the patient is afebrile and if there are multifocal neurological signs, even when a primary tumor is not obvious.