[Malignant melanoma of the meninges--MR and CT diagnosis]

Malignant melanoma of the meninges is a rare neoplasm derived from melanocytes of the cranial or spinal meninges. Histologically classified as grade IV tumours, malignant melanoma may present either as a diffuse meningeal neoplasm, first described by Virchow in 1859, or as a circumscribed tumour attached to the meninges. Although diagnosis is rarely established prior to surgery or autopsy, MR and CT may provide indispensable information probably leading to earlier diagnosis. In 4 patients, diagnosis of a primary meningeal melanoma was based on MR and CT findings and histology. Histology was obtained in 3 cases by surgery, in one patient by autopsy and showed a melanotic and an amelanotic malignant melanoma in 2 patients each. Autopsy was carried out in 3 cases after survival of 4, 5, and 18 months; in a single case, the follow-up period is almost 3 years.