Identifying Large-Vessel Vasculitis in Polymyalgia Rheumatica: Key Clinical and Laboratory Red Flags

Potential red flags for large-vessel vasculitis in isolated polymyalgia rheumatica (PMR) include inflammatory back pain, significant pelvic involvement, widespread lower extremity pain, marked inflammatory response indicated by specific lab test abnormalities, and insufficient response to 20 mg/day of prednisone, according to an editorial published in Clinical and Experimental Rheumatology.

PMR is characterized by severe pain and stiffness in the shoulders, hips, neck, and upper arms. It often presents suddenly and is typically easy to suspect clinically when common symptoms are present. PMR may occur alone or alongside giant cell arteritis (GCA), a type of vasculitis affecting larger vessels. Despite PMR being more common, around 40-50% of GCA patients also show PMR symptoms, and PMR can sometimes precede visible signs of GCA. Imaging techniques like ultrasound (US) and 18F-FDG PET/CT scans have expanded the understanding of GCA, showing it can affect vessels outside the cranial region without cranial symptoms.

A study involving 84 PMR patients without GCA signs found significant vascular uptake indicating LV vasculitis in half through FDG-PET/CT, though without clinical correlation to predict LV vasculitis. Comparing isolated PMR with PMR linked to GCA revealed differences in age, symptom severity, and laboratory markers, suggesting a stronger inflammatory response might indicate underlying LV vasculitis.

Early imaging tests are advised for suspected LV vasculitis, with US recommended as the initial step. However, temporal artery biopsy's effectiveness in diagnosing subclinical GCA in PMR cases is limited. PET/CT is useful, especially for atypical symptoms or pelvic girdle involvement, indicating a potential LV vasculitis presence. Studies show a higher prevalence of subclinical GCA detected via PET/CT than ultrasound or biopsy. Yet, there's a need for more research to find reliable predictors of GCA in isolated PMR cases. Meanwhile, recognizing potential red flags and employing imaging tests, particularly US and PET/CT, is crucial for early detection and management of GCA in PMR patients.

Miguel Angel Gonzalez-Gay, Rheumatology Division, IIS-Fundación Jiménez Díaz in Madrid, Spain, and coauthors explained, “since severe ischaemic manifestations of GCA can occur in patients who present as isolated PMR, we recommend periodic evaluation of patients with PMR for early identification of the onset of ischaemic manifestations of GCA.”

Reference

González-Gay MA, Vicente-Rabaneda EF, Heras-Recuero E, Castañeda S. Polymyalgia rheumatica: when should we suspect an underlying large vessel vasculitis? Clin Exp Rheumatol. 2023;41(4):774-776. doi:10.55563/clinexprheumatol/3bozph