"The melanocytic cells found in the subarachnoid space are believed to arise from leptomeningeal melanocytes of neural crest origin 1. Sometimes meningeal melanocytosis can extend to involve the perivascular spaces, importantly without direct invasion into the brain 1. The cells appear bland without atypia, necrosis or significant mitotic activity. If these features are found then a diagnosis of meningeal melanomatosis should be made 1."