SS can also be diagnosed by cerebrospinal fluid (CSF) examination through xanthochromia, elevated presence of RBCs, high iron and ferritin concentrations, and elevated levels of the proteins Tau, beta-amyloid (Ab42), and glial fibrillary acidic protein (GFAP), but in most of the cases CSF is normal [18]. Here, GFAP is linked to synovial sarcoma.