BACKGROUND: Fibromyalgia (FM) is a common disorder of diffuse musculoskeletal pain. It is distinctly different from polymyalgia rheumatica (PMR), a disease seen in people over the age of 50 years. Hallmark features of PMR are the presence of elevated erythrocytes sedimentation rate (ESR) and/or C-reactive protein (CRP). These markers are normal in FM. Obesity in itself can be associated with elevated CRP and ESR, and when obese patients present with myalgia and elevated inflammatory markers, diagnostic confusion can ensue.

CASE REPORT: We describe a case of 38-year-old female with diffuse musculoskeletal pain and elevated ESR and CRP who was initially misdiagnosed with PMR and responded partially to steroids. She developed severe adverse effects from chronic steroid use. She was ultimately diagnosed with FM.

CONCLUSIONS: We highlight features to help clinicians avoid the pitfall of diagnosing PMR in young obese patients with FM and elevated inflammatory markers. In this case report, we discuss the features of FM, PMR, PMR-like symptoms presentation, and the association of obesity with elevated inflammatory markers.

Keywords: C-Reactive Protein, Fibromyalgia, Obesity, Polymyalgia Rheumatica, Blood Sedimentation, Diagnostic Errors, Myalgia