CXCL13 and glioblastoma: Additionally, there were two false positive cases of GBM and brain involvement of Sjögren's syndrome in the 4‐marker (CXCL13, IL‐10, β2‐MG, and sIL‐2R) and 3‐marker (CXCL13, IL‐10, and β2‐MG) algorithms.