Rheumatic mimics and selected triggers of fibromyalgia.

Fibromyalgia is a chronic pain syndrome of unknown etiology characterized by diffuse pain and tender points, which have been present for more than 3 months. Many patients with systemic illnesses can have diffuse pain similar to that found in fibromyalgia, including rheumatic diseases such as polymyalgia rheumatica, rheumatoid arthritis, idiopathic inflammatory myopathy, systemic lupus erythematosus, and joint hypermobility. Osteomalacia and thyroid disease are also in the differential diagnosis of diffuse pain and are imminently treatable. In addition, there has been interest throughout the past 10 years in infectious diseases including hepatitis C, Lyme disease, coxsackie B, HIV, and parvovirus infection, which may cause or trigger fibromyalgia. This paper provides a framework to use when identifying these diseases as part of the evaluation of a patient with chronic widespread musculoskeletal pain.