Following is the ACR diagnostic criteria for Giant Cell Arthritis (GCA) A patient with 3 or more of the following signs is diagnosed with Giant Cell Arthritis (GCA). - Age over 50 years - New onset headache - Temporal artery abnormalities i.e. irregularities of arterial wall including tenderness to palpitation or decreased pulsation) - Erythrocyte Sedimentation Rate (ESR) > 50mm/hour - Abnormal Temporal Artery Biopsy (TAB) i.e. mononuclear cell infiltration or granulomatous inflammation