WED 243 Enhancing our knowledge of leptomeningeal disease – a case of DL-GNT

A 57-year-old woman presented with several weeks of headache associated with neck stiffness, drowsiness and nausea. She developed diplopia with right-sided 6th nerve palsy and subsequently developed a complex ophthalmoplegia and right-sided ptosis.Repeated lumbar punctures showed high opening pressures of up to 60 cm H2O and high protein levels up to 2.48 g/L. She developed episodes of marked loss of responsiveness but EEGs showed only generalised slowing. Brain imaging was essentially normal. An MRI Spine showed an enhancing intramedullary hyperintensity T8-T10 with overlying meningeal enhancement. A CT-PET scan revealed uptake along the cord consistent with diffuse infiltration or a meningitis – biopsy was inconclusive but macroscopically the dura was thickened with calcification observed on the spinal cord surface. A brain biopsy did not aid diagnosis and unfortunately the patient deteriorated with increasing severity of headaches and drowsiness. She died after a number of cardiorespiratory arrests.At post-mortem, thickened meninges showed a glioneuronal cell infiltrate and a diagnosis of diffuse leptomeningeal glioneuronal tumour (DL-GNT). WHO recently described DL-GNT in the 2016 update of CNS tumour classification. Previous case reports of this rare disease have concerned adults and children. DL-GNT should be considered in cases of radiological leptomeningeal enhancement and high CSF protein levels.