Leptomeningeal dissemination of low-grade intramedullary gliomas: about one case and review.

Leptomeningeal (LM) dissemination arises rarely in patients with low-grade gliomas. Few cases of LM dissemination of spinal cord low-grade gliomas have been reported in children. Here, we report a case of an intramedullary spinal cord low-grade glioma occurring in an adult presenting by LM dissemination. A 57-year-old man presented with a history of headaches and visual acuity deterioration. Neurological examination revealed mental confusion, decreasing left limb strength and left positive Babinski sign. Lumbar puncture showed low CSF glucose, high CSF protein and no tumor cells. Spinal MRI revealed an intramedullary spinal lesion with a diffuse leptomeningeal enhancement. A spinal meningeal biopsy showed arachnoiditis with isolated atypical cells which were cytokeratin immunopositive. A differential diagnosis was proposed between arachnoiditis close to an infectious process or close to meningeal carcinomatosis. An intramedullary biopsy was programmed but the patient died 1 month after biopsy. The post-mortem examination showed thickened leptomeninges and an ill-circumscribed intramedullary grey lesion. Histological examination revealed a low-grade glial neoplasm composed of monomorphous spindle "piloid" cells with diffuse dissemination to leptomeninges. Glial fibrillary acidic protein immunostaining showed scattered immunoreactive cells. Clinical and pathological features of this case are unusual. Pathogenesis and prognosis of low-grade gliomas with LM dissemination are poorly understood. This case, like cases occurring in children, cannot easily be classified in the present WHO system of classification of CNS tumors. Spinal low-grade gliomas with LM dissemination may represent a possible distinctive clinico-pathological entity.