The cardinal feature of fibromyalgia (FM) is chronic, widespread pain that is not explained by another rheumatic or systemic disorder. Explicit in this definition is the exclusion of other conditions that can present with widespread pain. Thus, although the differential diagnosis of FM may potentially become quite complicated, it should actually be relatively simple [1,2].
Rather than worrying about every disease that can cause musculoskeletal pain, the clinician should focus on the characteristic features of FM:
●Pain above and below the waist, which is bilateral and axial for at least three months
●Somatic complaints including fatigue and sleep, mood, and cognitive disturbance
These symptoms are often present in many other diseases. However, these other conditions, such as infection, often either are transient or manifest abnormal physical and laboratory findings. In FM, the physical examination, other than tenderness in muscles and soft tissue (tender points), is unrevealing and laboratory and imaging are unremarkable.