TOPLINE

In patients with apparently isolated giant cell arteritis (GCA), FDG PET-CT detected subclinical polymyalgia rheumatica (PMR) in nearly 56% of patients, and these patients had milder musculoskeletal inflammation but greater involvement of large vessels than patients without PMR.

METHODOLOGY

• Researchers conducted a retrospective cohort study at a Spanish hospital to assess the prevalence and clinical features of subclinical PMR in patients with newly diagnosed GCA with follow-up to at least 1 year.
• They reviewed records of 168 patients aged 50 years or older (mean age at diagnosis, 74.7 years; 66% women) who were diagnosed with GCA between January 2005 and September 2024. All patients underwent baseline FDG PET-CT at the time of diagnosis.
• FDG uptake at typical PMR sites was visually graded using uptake in the liver as the reference. Subclinical PMR was defined as grade ≥ 2 uptake in the bilateral shoulders or trochanteric bursae/ischial regions, along with uptake in at least one additional site.
• Patients were classified as having clinical PMR (both symptoms and PET findings), subclinical PMR (PET-CT findings without symptoms), or pure GCA (no PMR), and several published PET-based PMR scoring systems were applied retrospectively.

TAKEAWAY

• Among 168 patients with GCA, 66 had clinical PMR, 57 had asymptomatic subclinical PMR, and 45 had no PMR. Many patients with subclinical PMR met the standard PET-based criteria for PMR.
• Patients with GCA and subclinical PMR had greater involvement of large vessels than those with pure GCA, particularly in the thoracic aorta (75.4% vs 48.9%), abdominal aorta (56.1% vs 15.6%), and supra-aortic trunks (73.7% vs 42.2%; P < .05 for all).
• Patients with subclinical vs clinical PMR had a lower mean score for FDG uptake at typical PMR sites (6.07 vs 8.21; P = .0001) and had less frequent uptake in the lumbar interspinous bursae (36.8% vs 62.1% of patients) and hips (10.5% vs 28.8% of patients; P < .05 for both).
• Relapse rates at 12 months did not differ significantly between the groups.

IN PRACTICE

“Similar to previous imaging evidence of subclinical vasculitis in patients with isolated PMR, our study demonstrates that subclinical PMR features are frequent in apparently isolated GCA. This reciprocal finding reinforces the notion that GCA and PMR represent distinct clinical expressions of a shared inflammatory process rather than independent conditions ,” the authors wrote.

SOURCE

This study was led by Javier Narváez, MD, PhD, Hospital Universitario de Bellvitge, Barcelona, Spain. It was published online on June 2, 2026, in Rheumatology.

LIMITATIONS

This study was retrospective and observational. Physicians were aware of PET results when making the diagnosis. Many patients received glucocorticoids before imaging, which may have reduced FDG uptake and underestimated the true prevalence of subclinical PMR.

DISCLOSURES

This study did not receive any specific funding. The authors declared having no competing interests. 

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.