Whole-body MRI of patients with polymyalgia rheumatica identifies a distinct subset with complete patient-reported response to glucocorticoids.

OBJECTIVES: To determine whether whole-body MRI defines clinically relevant subgroups within polymyalgia rheumatica (PMR) including glucocorticoid responsiveness. METHODS: 22 patients with PMR and 16 with rheumatoid arthritis (RA), untreated and diagnosed by consultant rheumatologists, underwent whole-body, multiple-joint MRI, scored by two experts. Patients with PMR reported whether they felt 'back to normal' on glucocorticoid therapy and were followed for a median of 2 years. RESULTS: All patients with PMR were deemed to respond to glucocorticoids clinically. A characteristic pattern of symmetrical, extracapsular inflammation, adjacent to greater trochanter, acetabulum, ischial tuberosity and/or symphysis pubis, was observed in 14/22 of the PMR cases. In PMR, this pattern was associated with complete glucocorticoid response (p=0.01), higher pretreatment C-reactive protein (CRP) and serum interleukin-6 (IL-6), and better post-treatment fatigue and function. Only 1/14 in the extracapsular group could stop glucocorticoids within 1 year, compared with 4/7 of the others. A score derived from the five sites discriminating best between PMR and RA correlated with IL-6 (p<0.002). IL-6 levels ≥16.8 pg/mL had 86% sensitivity and 86% specificity for the extracapsular MRI pattern. CONCLUSIONS: A subset of patients with rheumatologist-diagnosed PMR had a characteristic, extracapsular pattern of MRI inflammation, associated with elevated IL-6/CRP and with complete patient-reported glucocorticoid responsiveness.

Diagnosis and management of giant cell arteritis and polymyalgia rheumatica: challenges, controversies and practical tips.

Giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) are inflammatory rheumatic diseases that may present to a variety of disciplines and specialities. The mainstay of treatment is glucocorticoids (steroids); together PMR and GCA now represent one of the most common reasons for medium-to-high dose, long-term glucocorticoid treatment in primary care. However, adverse effects of glucocorticoids are common in these patients. Management of both diseases involves balancing the symptoms and risks of the disease against the adverse effects and risks of glucocorticoids. The crucial first step in management is to make a firm, well-documented diagnosis, since once glucocorticoids are started they can mask the symptoms of a number of other diseases. Diagnosis however can be challenging and there are still substantial gaps in the evidence for treatment.