Glial Fibrillary Acidic Protein (GFAP) is a 50kD intra-cytoplasmic filamentous protein of the cytoskeleton in astrocytes. It has demonstrated to be the most specific marker for cells of astrocytic origin. GFAP, a class-III intermediate filament, is a cell-specific marker that, during the development of the central nervous system, distinguishes astrocytes from other glial cells. GFAP immunoreactivity has been shown in immature oligodendrocytes , epiglottic cartilage, pituicytes, papillary meningiomas, myoepithelial cells of the breast and in non-CNS: Schwann cells, salivary gland neoplasms, enteric glia cells and metastasizing renal carcinomas. It