PRIMARY LEPTOMENINGEAL MELANOMA - AN UNUSUALLY AGGRESSIVE TUMOR IN CHILDHOOD

PRIMARY MALIGNANT MELANOMA of the leptomeninges of the central nervous system is a rare and aggressive tumor in children. We report our experience from 1964 to 1990 with this tumor in eight children. The mean age at diagnosis was 4.9 years (range, 1.3 to 13 yr). Five children presented with signs and symptoms of raised intracranial pressure from hydrocephalus secondary to tumoral obliteration of the basal cisterns, but the time from the initial symptomatology to diagnosis was frequently delayed. Three patients in this series had hairy nevi in association with their leptomeningeal melanoma. Cerebrospinal fluid (CSF) analysis typically showed raised opening pressures, decreased glucose, and increased protein concentrations. Malignant melanoma cells were found in the CSF in three patients. Confirmatory radiographic examinations included air encephalography, myelography, and computed tomographic and magnetic resonance scanning. Four patients were treated with lumboperitoneal shunts, and one patient was treated with a ventriculoperitoneal shunt for hydrocephalus. Two patients underwent craniotomies and subtotal excisions of their tumors. In seven patients, a definitive diagnosis of leptomeningeal melanoma was made by pathological examination of tissues sent at surgery or at post mortem. In one case, the diagnosis was established by a detailed cytological analysis of the CSF. Four children died of fulminant disease and tumor spread before treatment could be instituted. The four children who received treatment had a combination of radiation therapy and chemotherapy. One child received intrathecal methotrexate. The two children with the longest survivals (2 and 3 yr, respectively) received cisplatinum and dimethyltriazenoimidazole carboxamide in addition to craniospinal irradiation. We conclude that primary leptomeningeal melanoma continues to be a rare and difficult tumor to diagnose and treat in childhood. The widespread availability of magnetic resonance imaging may facilitate diagnostic accuracy preoperatively. We have seen improved survival in recent times with a combination of chemotherapy and conventional craniospinal irradiation.