Granular Cell Tumor : S-100
Immunohistochemically, granular cell tumors show strong positivity for S-100 protein as well as NSE, laminin, calretinin, myelin proteins (P0, P2), and CD68. They are negative for neurofilament protein and GFAP. Differential diagnosis: Granular cell tumor should be distinguished from rhabdomyoma (presence of glycogen and cross striations), hibernoma (lipid droplets), and fibroxanthoma (lipid droplets), and reactive histiocytic proliferations at sites of trauma or surgery. Treatment: Most granular cell tumors behave in a benign fashion and are cured by simple resection.