Giant Cell Arteritis Phenotypes Show Different Patterns of Arterial Involvement

Giant cell arteritis (GCA) encompasses a broader clinical spectrum than previously recognized, with distinct cranial and extracranial phenotypes that exhibit different patterns of arterial involvement, according to study results published in Arthritis Research & Therapy.

Researchers conducted a retrospective study involving data from 140 patients with newly diagnosed GCA who underwent ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG PET-CT) scans between January 2005 and March 2023. They aimed to investigate differences in arterial involvement patterns between patients with predominantly cranial vs isolated extracranial GCA phenotypes.

Patients with the predominantly cranial phenotype presented with craniofacial ischemic symptoms at diagnosis or during follow-up while the isolated extracranial group did not.

Among the 140 patients (64.3% women; mean age, 74.9 years) included in the analysis, 70.7% (n=99) exhibited cranial ischemic manifestations and 29.3% (n=41) presented with the isolated extracranial phenotype. A total of 93 patients received temporal artery biopsy (TAB), among which 53 (57%) had positive results; 18 out of 63 patients (27.3%) yielded positive results on color Doppler ultrasounds of the temporal arteries. Notably, ¹⁸F-FDG PET-CT scans showed large-vessel involvement among 82.1% (n=115) of patients, including the aorta and other major arteries.

The predominantly cranial phenotype was associated with a shorter diagnostic delay (43±51 days vs 243±688; P =.004) and higher TAB positivity (62.3% vs 25%; P =.0001), compared with the isolated extracranial group. In contrast, ¹⁸F-FDG PET-CT scans were universally positive among extracranial cases (100% vs 74.7%; P =.0001).

Patients with the isolated extracranial vs predominantly cranial phenotype were younger (71.1±6.9 vs 76.4±7.8 years; P =.0001), exhibited higher thoracic aortic involvement (92.7% vs 58.6%; P =.001), and had greater abdominal aortic (61% vs 35.4%; P =.005) and iliac artery (56.1% vs 30.3%; P =.004) involvement. Subclavian artery involvement was more frequent among extracranial cases (65% vs 43.4%; P =.021), while patients with the predominantly cranial phenotype showed greater vertebral artery involvement (39.4% vs 10%; P =.001).

Glucocorticoid treatments varied, with intravenous methylprednisolone more common among cranial vs extracranial cases (30.3% vs 0%; P =.001). Polymyalgia rheumatica symptoms were more frequent among patients with the isolated extracranial phenotype (58.5% vs 38.4%; P =.029), though systemic symptoms were similarly prevalent.

Study limitations include the observational and retrospective design, selection bias, and the potential overestimation of diagnostic accuracy via imaging studies.

The study authors concluded, “These findings may explain atypical symptoms such as inflammatory lower back pain or limb claudication and the increased risk of aortic complications in extracranial GCA.”

This article originally appeared on Rheumatology Advisor