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Suspected extracranial large-vessel giant cell arteritis — SCE Rheumatology MCQ

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ModerateGiant Cell ArteritisSuspected extracranial large-vessel giant cell arteritisSCE Rheumatology

A 71-year-old woman presents with 6 weeks of fatigue, night sweats, a 4 kg weight loss and bilateral upper-arm aching brought on by hanging washing, which resolves with rest. She has no headache, scalp tenderness, jaw claudication, polymyalgic morning stiffness or visual symptoms. The right radial pulse is reduced, and systolic blood pressure is 24 mmHg lower in the right arm than the left. ESR is 82 mm/hour, CRP 96 mg/L and platelet count 548 × 10^9/L. Blood cultures are negative, and there is no clinical focus of infection. Extracranial large-vessel giant cell arteritis is suspected, glucocorticoid treatment is commenced, and a vascular imaging service with specific expertise in giant cell arteritis ultrasonography is available the same day. Which investigation is the most appropriate first test to support the diagnosis?

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Correct answer: C — Duplex ultrasonography of the temporal and axillary arteries

The constitutional syndrome, markedly raised inflammatory markers, thrombocytosis, bilateral arm claudication, pulse abnormality and inter-arm blood-pressure difference indicate a high probability of extracranial large-vessel GCA despite the absence of cranial symptoms. Current EULAR imaging recommendations designate expert ultrasonography of both temporal and axillary arteries as the first imaging test in all suspected GCA. Including the axillary arteries is particularly important in this phenotype and can also identify subclinical cranial involvement. Temporal ultrasonography alone omits the vascular territory most strongly implicated clinically. FDG-PET/CT is a strong alternative for detecting extracranial mural inflammation and may define the full disease distribution, but it is not first choice when prompt expert temporal-and-axillary ultrasonography is available. CT angiography is useful for mapping luminal stenosis, occlusion, aneurysm or other structural damage, but is less appropriate than ultrasound or FDG-PET for the initial demonstration of active mural inflammation. Temporal artery biopsy remains a valid diagnostic test where expert imaging is unavailable or findings are inconclusive, but its yield may be lower in a predominantly extracranial phenotype. Diagnostic imaging should be obtained promptly but must not delay glucocorticoid initiation.

Reference: EULAR recommendations for the use of imaging in large vessel vasculitis in clinical practice: 2023 update (Published online 7 August 2023; print 2024) — https://ard.bmj.com/content/83/6/741 British Society for Rheumatology guidelines: Giant cell arteritis (Page checked August 2026) — https://www.rheumatology.org.uk/guidelines/guidelines_other/rcnbiologics