Fibromyalgia (FM) is characterized by chronic widespread musculoskeletal pain and tenderness. FM is present in 2-5% of the general population but it occurs in 20% or more in patients with degenerative or inflammatory rheumatic disorders. Similarly chronic infections (Hepatitis C, HIV, Lyme disease, Parvovirus B19, Epstein Barr virus), Metabolic (thyroid disorders, Hyperparathyroidism) or psychiatric disease associated with musculoskeletal pain can mimic FM or serve as trigger for development of FM.