P14.87 Leptomeningeal dissemination in high grade glioma: Correlation of MRI, cytology and standard CSF indices

Abstract

Abstract BACKGROUND Only few studies report the incidence of leptomeningeal dissemination (LMD) in patients with high grade glioma (HGG), although LMD is not a rare condition of recurrence. We aimed to describe the diagnostic features and treatment modalities in a series of patients treated for HGG in our institution. METHODS Review of clinical presentation, radiological features and CSF analysis in a case series. RESULTS 17 patients from our institution were diagnosed with LMD. The diagnosis of LMD was based on magnetic resonance image and/or cerebrospinal fluid (CSF) analysis. The spectrum of clinical presentation was broad, mainly intracranial hypertension, impaired general condition, pain, worsening of pre-existing symptoms, and epileptic seizures. Median time from onset of clinical deterioration to diagnosis of LMD was 3 weeks (0–16). Leptomeningial involvement was reported in 6/17 at initial MRI reading, whereas reassessment with careful comparison to previous MRI showed signs of LMD in all patients. CSF analysis revealed pleocytosis (11/17), high proteinorrachia (13/17), elevated lactate levels (15/16), low glucose levels (5/17), and increased CSF pressure (5/9). Nevertheless, diagnostic accuracy of initial CSF cytological analysis was low (2/17). A reassessment of the specimen by an experienced neuropathologist disclosed 1 additional positive and 1 additional suspect cytology. After diagnosis of LMD, salvage treatments comprised Bevacizumab, Lomustine, Fotemustine, liposomal cytarabine and best supportive care. The median overall survival after the diagnosis was 3 months. DISCUSSION AND CONCLUSIONS LMD in HGG is not a rare condition of recurrence, and its outcome is poor. It remains a diagnostic challenge, as it may be overlooked on MRI follow-up at its early stage. In case of clinical progression with no overt cause reported on MRI, we recommend careful second MRI reading. In case of doubt lumbar puncture should be performed in order to prove LMD and eliminate infection (i.e. HSV). Upon standard CSF indices, elevated lactate levels should give rise to the suspicion of LMD. Cytological CSF analysis seems to be of low diagnostic yield: This may be improved by faster processing after sampling and by standardized workup including staining with IDH, GFAP and Olig2.