Primary leptomeningeal melanomatosis: early leptomeningeal enhancement on MRI.

One unusual case of primary leptomeningeal melanomatosis is presented. The patient, 53-year-old male, was admitted to our observation for 1 month history of psychasthenia and amnesia. Despite several polyspecialistic clinical, neuroradiological and cytological examinations, conclusive diagnosis was made only with a biopsy of leptomeningeal nodule. The present case allows as to identify 2 stages in the evolution of primary diffuse leptomeningeal melanomatosis. The initial phase is characterized by slight mental impairment without hydrocephalus; during the later phase there is severe, diffuse neurological impairment and both CT and MRI show hypercaptation of the intracranial leptomeninges and multiple, leptomeningeal tumoral nodules.