Contrast-enhanced MR imaging of neurocutaneous melanosis.

A previously healthy 10-year-old girl presented with a 3-week history of headaches, vomiting, and diplopia. Physical examination revealed multiple pigmented cutaneous nevi, bilateral sixth nerve palsies, and papilledema. No pigmented intraocular lesions were found. Unenhanced CT and MR scans were unremarkable. An opening pressure of 38 em H20 was found at lumbar puncture with no abnormalities on CSF analysis. Treatment with corticosteroids for a presumed diagnosis of pseudotumor cerebri did not result in clinical improvement A lumboperitoneal shunt was placed 4 months later without improvement in the patient's symptoms. Repeat CSF analysis revealed a pleocytosis with a mononuclear cell predominance, hypoglycorrhachia, and an elevated protein. CSF cultures were negative. Cranial (Figs. 1A and 18) and spinal (Fig. 2) MR imaging performed with a 1.5-T superconducting GE Signa imaging system after the administration of gadopentetate dimeglumine revealed marked diffuse leptomeningeal enhancement A T2-weighted MR image was unremarkable (Fig. 1 C). No focal mass or parenchymal invasion was demonstrated. Primary CNS melanoma was suspected. Left frontal cerebral and meningeal biopsies were performed, which displayed a proliferation of cells, some containing melanin, in thickened leptomeninges, consistent with melanosis. There was no evidence of gross atypia or cerebral invasion. Multiple pigmented cutaneous nevi were excised, all displaying benign histology. Following the placement of an Ommaya reservoir, the patient received 10 courses of intrathecal interleukin-2 (IL-2) and lymphokine activated killer (LAK) cells. An MR scan 1 0 months after initial presentation displayed increased ventricular size, correlating with symptoms of increasing nausea, vomiting, and mental confusion. A ventriculoperitoneal shunt was placed. A follow-up cranial MR scan (Fig. 3) after gadopentetate dimeglumine administration revealed persistent diffuse leptomeningeal enhancement unchanged from the examination depicted in Figures 1 and 2. Ventricular size had returned to normal.