The differential diagnosis of generalized pain

Patients whose symptoms include widespread, diffuse musculoskeletal pain ar e commonly referred for rheumatological evaluation, even when the underlyin g cause may lie outwith the remit of rheumatology. A diagnosis of fibromyal gia may seem highly probable even from the referral letter, or after a few leading questions during the consultation. However, the lack of specificity of the many symptoms associated with widespread pain means that other diag noses have to be considered. The history and examination must bear in mind alternative and concomitant musculoskeletal disorders, such as mild systemi c lupus erythematosus, polyarticular osteoarthritis, rheumatoid arthritis, polymyalgia rheumatica, hypermobility syndromes and even osteomalacia. Non- rheumatological diseases may also have symptomatic similarities to fibromya lgia, including neoplastic and neurological diseases, hypothyroidism and ot her endocrine disorders, chronic infections, as well as a variety of psychi atric conditions. A rational approach to investigation will usually allow o ther diagnostic possibilities to be excluded without reinforcing the abnorm al illness behaviour so common in chronic pain states.