LAUSR

© BMJ Publishing Group Limited 2021. No commercial reuse. See rights and permissions. Published by BMJ. DESCRIPTION A 74yearold woman presented with fever, jaw claudication and bilateral temporal pain lasting for 1 week. On examination, the bilateral temporal arteries (TAs) were nodularly swollen, tender and hypopulsatile (figure 1A). A blood test showed elevated white cell count (9.33×10/L), high erythrocyte sedimentation rate (119 mm/h) and high level of Creactive protein (11.03 mg/dL). Ultrasound (US) showed wall thickening (halo sign) and stenosis of the bilateral TAs (figure 1B,C). Contrastenhanced MRI showed thickening of the TA bilaterally. Biopsy of the left TA led to the diagnosis of giant cell arteritis (GCA). Immediately after the biopsy, prednisolone at 1 mg/kg was administered orally, and her symptoms rapidly resolved. GCA is a vasculitis of large and mediumsized blood vessels. Symptoms include headache, visual disturbance, jaw claudication and fever. Physical examination shows thickening, tenderness and pulselessness in the TA. However, any one of these findings alone is not sufficient for diagnosing or ruling out GCA. US is useful for diagnosis with a sensitivity of 77% and specificity of 96%. TA US in GCA reveals four characteristic findings: (1) ‘halo sign’, which is a hypoechoic ring around the lumen reflecting vessel wall thickening, (2) ‘compression sign’, which is contrasting echogenicity induced between the artery wall and surrounding tissue by TA compression, (3) stenosis and (4) occlusion. Of these findings, the halo sign is the most useful for diagnosis. However, it is important to investigate the TAs bilaterally and as completely as possible because the lesions are often segmental and only evaluating part of the TAs may result in a false negative. When GCA is suspected on the basis of physical examination, TA US should be checked for characteristic findings including the halo sign.