Primary leptomeningeal primitive neuroectodermal tumor: A difficult entity to diagnose.

A 25-year-old male presented with difficulty in walking, loss of vision, and seizures. A clinical possibility of craniospinal meningeal pathology was considered. On computed tomography (CT) scan and magnetic resonance imaging, there was an enhancement of leptomeninges with few ring-enhancing lesions in both frontal lobes and right frontoparietal region. He was evaluated for low backache and occipital headache 2½ years earlier and was found to have communicating hydrocephalus on CT scan. He underwent ventriculoperitoneal shunt and was followed up with CT scans. Meningeal biopsy was done in the present admission, and there was a diffusely infiltrating small round cell tumor. Immunohistochemistry was done, and the tumor cells were found to be negative for glial, mesenchymal, melanotic, and lymphoid markers. The cells were positive for neuron-specific enolase, chromogranin, and vimentin. A diagnosis of primitive neuroectodermal tumor involving the meninges was made. A possibility of primary leptomeningeal tumor extending to parenchyma was considered based on the clinical progression. Patient was treated with chemotherapy and radiotherapy. He improved partially and was stable at 3-year follow-up.