Meningeal Melanocytosis

**Semantic type:** Neoplastic Process

**Definition:** A diffuse or multifocal proliferation of uniform nevoid polygonal cells in the leptomeninges. Cells may spread into the Virchow-Robin spaces without frank invasion of the brain. Diffuse melanocytosis carries a poor prognosis even in the absence of histologic malignancy. (WHO)

**Synonyms:** - Diffuse Melanocytosis - Diffuse Melanosis - Diffuse Meningeal Melanocytosis - Diffuse melanocytosis