PMEL and neurofibroma: There are many theories to explain MS pathogenesis, one of them is explained by the common developmental origin of melanocyte and Schwann cells.3Other possible differential diagnoses include neurofibroma, pigmented dermatofibrosarcoma, melanocytoma, and malignant melanoma.5MS stains positive for S-100, leu-7, HMB-45, and vimentin and negative for glial fibrillary acidic protein, epithelial membrane antigen, and creatine kinase.8magnetic resonance imaging (MRI) has a great role in MS diagnosis because of the paramagnetic feature of melanin.