Musculoskeletal manifestations of systemic lupus erythematosus.

MSK is the most common and impactful symptom of lupus at a population level. It has a variety of different presentations, but joint swelling is often not present despite imaging-proven synovitis. Imaging with US and MRI has been shown to improve detection of inflammation and identify treatment-responsive patients. In contrast, the SLEDAI shows poor sensitivity, specificity, and responsiveness. While BILAG and SLE-DAS are superior, they are still less accurate than imaging. These issues may explain why the evidence for conventional and biologic therapies for MSK lupus is complex. In clinical practice, physicians must take care not to underestimate MSK inflammation and consider using imaging. Future research should investigate new therapeutic targets specifically for synovitis and more sensitive outcome measures and trials to evaluate them.