From the Guidelines
Giant cell arteritis (GCA) is best diagnosed through a combination of clinical evaluation, laboratory tests, and a temporal artery biopsy, with the biopsy being the gold standard test, as recommended by the 2021 American College of Rheumatology/Vasculitis Foundation guideline 1. The diagnosis of GCA involves several steps, including:
- Clinical evaluation to identify symptoms such as headaches, scalp tenderness, vision loss, and jaw claudication
- Laboratory tests, including erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), which are usually significantly elevated in GCA
- Temporal artery biopsy, which involves removing a small section of the temporal artery for microscopic examination to look for inflammation and giant cells
- Additional testing, such as ultrasound of the temporal arteries, MRI, CT angiography, or PET scans, to evaluate larger vessels and detect any potential complications
According to the guideline, a unilateral temporal artery biopsy is recommended as the initial diagnostic test, with bilateral biopsies considered if the symptoms are not clearly localized to one temporal artery 1. The guideline also recommends obtaining a temporal artery biopsy specimen within 2 weeks of starting oral glucocorticoids, as this maximizes the likelihood of detecting histopathologic changes indicative of GCA 1. In terms of the biopsy specimen, a long-segment temporal artery biopsy specimen (>1 cm) is preferred over a short-segment specimen (<1 cm), as it increases the diagnostic yield and reduces the risk of missing the diagnosis 1.
Overall, the diagnosis of GCA requires a comprehensive approach, including clinical evaluation, laboratory tests, and imaging studies, with temporal artery biopsy being the gold standard test. Prompt treatment with high-dose corticosteroids should not be delayed if GCA is strongly suspected, as untreated GCA can lead to permanent vision loss 1.
From the Research
Giant Cell Arteritis Diagnosis
- Giant cell arteritis (GCA) is a systemic immune-mediated vasculitis affecting medium-sized and large-sized arteries, characterized by headache, jaw claudication, visual loss, and constitutional symptoms 2.
- The gold standard for diagnosis is temporal artery biopsy (TAB), with a specificity of 100% and a sensitivity of 77% 3.
Temporal Artery Biopsy
- TAB is recommended to be performed within 1 week of starting corticosteroid therapy to reduce the false-negative rate 3.
- The temporal artery should be cut to a length of 20-30 mm, and serial pathological sections should be prepared to improve sensitivity 3.
- A biopsy length of ≥15 mm increases the odds of a positive TAB result, and an erythrocyte sedimentation rate (ESR) ≥50 mm/h is a strong predictor for a positive TAB result 4.
Diagnostic Tests
- Additional diagnostic tests include blood tests (erythrocyte sedimentation rate, ESR; C-reactive protein, CRP; platelets) and imaging modalities (ultrasound of the arteries; fluorescein angiography, FA; MRI; and positron emission tomography, PET) 2.
- Imaging technologies, such as DUS, CTA, MRA, and 18F-FDG-PET/CT, can be used as auxiliary methods for GCA diagnosis, but TAB remains the most specific diagnostic procedure 3, 5.
Treatment and Management
- The mainstay of management includes high-dose corticosteroids, and additional cytotoxic drugs, antitumor necrosis factor monoclonal antibody, and antiplatelet aggregation therapy may be used 2.
- The goal of treatment is to prevent ischemic damage and halt progression of visual loss in the affected eye and prevent involvement of the fellow eye 2.