Primary melanocytoma (benign;also known as cellular blue nevus or melanotic schwannoma) or diffuse malanosis are very rare conditions of the leptomeninges.

• 脑膜或脊膜部位的原发黑色素细胞瘤（良性，又称细胞性蓝痣或黑色素性施万氏瘤）或弥漫性黑变病在非常罕见。