A report of the natural history of leptomeningeal gliomatosis.

Primary leptomeningeal gliomatosis (PLG) is a rare condition, with fewer than 50 patients reported. Our report illustrates the natural history of PLG in full, from the prodromal phase of subacute meningitis to the final stages characterised by extensive nerve root infiltration, cranial nerve palsies and widespread peripheral neurogenic muscle wasting. We provide correlative neuroimaging with serial MRI, and present the first published positron emission tomography imaging of this condition. We emphasise the importance of considering PLG in the differential diagnosis of chronic aseptic meningitis, the difficulties of making the diagnosis ante mortem, and the utility and potential limitations of early meningeal biopsy in this condition.