Approach to the diagnosis of giant cell arteritis

GCA: giant cell arteritis; ESR: erythrocyte sedimentation rate; CRP: C-reactive protein; CDUS: color Doppler ultrasound; PMR: polymyalgia rheumatica; MRA: magnetic resonance angiography; CTA: computed tomography angiography; ACR: American College of Rheumatology; PET: positron emission tomography.

* While a high ESR and/or CRP increases the diagnostic significance of the above symptoms or signs, low or normal values do not exclude the diagnosis of GCA. However, an ESR and CRP should always be included as part of the initial diagnostic workup since they are almost always elevated in GCA. Refer to UpToDate content for additional details regarding laboratory data and GCA.

¶ A current or prior diagnosis of PMR increases the diagnostic significance of any of these symptoms or signs because of the association between GCA and PMR.

Δ High-dose glucocorticoids should be started once GCA is suspected. Refer to UpToDate content on the initial dose of glucocorticoids for GCA.

◊ For skilled operators, CDUS can be an acceptable alternative to the temporal artery biopsy as an initial diagnostic procedure. Scheduling of the temporal artery biopsy or CDUS should not delay initiation of treatment. Refer to UpToDate content for additional details regarding temporal artery biopsy and CDUS.

§ In a subset of patients with GCA, the disease is confined to the large vessels, and temporal artery biopsies in such patients are more often negative than positive.

¥ False negatives can occur with a temporal artery biopsy and CDUS. Refer to UpToDate content for additional details regarding the diagnostic accuracy of the temporal artery biopsy and CDUS.

‡ We routinely evaluate for large vessel involvement in all patients with newly diagnosed cranial GCA by performing CDUS of the epiaortic vessels (eg, carotid, subclavian, and axillary arteries). MRA or CTA is conditionally suggested by the ACR for evaluating for aortic involvement. Refer to UpToDate content on postdiagnostic imaging evaluation in patients with newly diagnosed cranial GCA.

† In some cases, GCA is confined to the large vessels (ie, the aorta and/or its first-order branches) instead of the more common form, which involves the cranial arteries. Imaging modalities include MRA, CTA, and PET. CDUS of the epiaortic vessels (eg, carotid, subclavian, and axillary arteries) can also be used to identify large vessel GCA. Selection of a given modality depends on the availability of local resources.

** High-dose glucocorticoid therapy in individuals with negative temporal artery biopsies and large vessel imaging must be carefully considered and reserved for selected patients with a classic clinical presentation of GCA and no other plausible alternative diagnoses. Clinical improvement following a brief trial of high-dose glucocorticoids is nonspecific and should not be relied upon for establishing the diagnosis of GCA.