Seronegative spondyloarthropathies

Abstract

Seronegative spondyloarthropathies (SNSA) affect genetically predisposed individuals and are triggered by environmental factors (Khan 2002). They consist of a group of closely related skeletal disorders characterized by the concurrence of arthritis and spondylitis, in which serological rheumatoid factor is absent, hence seronegative. SNSA include ankylosing spondylitis, Reiter's syndrome, psoriatic arthritis, arthritis associated with inflammatory bowel disease, and other rare forms of arthritides. The great majority of patients with one of these disorders demonstrate a positive test for HLAB27, although in psoriatic arthritis the positivity rate is low. Two clinical features have been shown to be useful in distinguishing SNSA from rheumatoid arthritis. One is oligoarthropathy that is asymmetrical with a predilection for the peripheral joints and the other is enthesopathy (the enthesis is the bone insertion of ligament and tendon). In addition and fundamentally, SNSA can be differentiated from rheumatoid arthritis on genetic, immunological, pathological and radiological bases as well as by symptoms and signs. Radiography is helpful and 99mTc-MDP bone scintigraphy is highly sensitive but not specific (Hays and Green 1972; Desaulniers et al. 1974). Fortunately, however, a recent study by Kim et al. (1999) has shown that pinhole scintigraphy can provide specific information on SNSA, Reiter's syndrome in particular.