MS-17 * PRIMARY LEPTOMENINGEAL PRIMITIVE NEUROECTODERMAL TUMOR

Abstract

BACKGROUND: Isolated primary leptomeningeal primitive neuroectodermal tumor (PNET) without intraparenchymal lesion is very rare and to-date few case reports have been published. We report a rare case of leptomeningeal PNET and highlight its neuroimaging features, outcome and literature review. DESIGN AND METHODS: A medline search was conducted for queries including “Children”, “PNET”, leptomeningeal involvement”. Relevant papers were selected for review. CASE REPORT: A 5-year-old female presented with 4-month history of continuous vomiting and repeated headache. CT scan demonstrated communicating hydrocephalus. External ventricular drain was place to relieve the intracranial pressure. An MRI of the brain and the spine showed diffuse leptomeningeal infiltration of the brain and the spinal cord with contrast enhancement. Lumbar cerebrospinal fluid analysis revealed elevated protein but no malignant cells. Pathology of the leptomeningeal biopsywas consistent with neuroepithelial neoplasm. Immunohistochemical stains revealed tumor cells strongly positive for synaptophysin and CD56, retained INI-1, but negative for CD99. Cytogenetical analysis revealed absence of EWS translocation and a diagnosis of primary leptomeningeal PNET was established. Patient received radiation therapy with 36 Gy to the craniospinal axis, concomitantly with vincristine and carboplatin . Follow-up brain and spine MRI showed near complete resolution of the leptomeningeal disease. Family opted not to pursue any therapy and she remains alive with residual disease 8 months since diagnosis. DISCUSSION: Leptomeningeal PNET carries poor prognosis with most patients succumbing to their disease. There are seven case reports in the literature with dismal outcome with survival range from 2 weeks to thirteen months post diagnosis .Rarity of this clinical entity had hindered profiling therapeutic guidelines. Prospective studies are needed to understand if the elusive molecular biology of this rare disease differs from other central PNET. This could help in strategizing optimal therapy and provide a meaningful improvement in the survival of these children.