PECAM1 and acral lentiginous melanoma: Immunohistochemically, ALM typically shows negative staining for epithelial membrane antigen (EMA), serum acidic binding protein S100, glial fibrillary acidic protein (GFAP), and desmin, while smooth muscle actin (SMA) and either CD34 or CD31 are markers for muscle cells and vascular endothelial cells, respectively.