Seronegative spondyloarthropathies are a group of disorders
characterized by the following:
Rheumatoid factor seronegativity
Involvement of the sacroiliac joints
Association with HLA-B27
Ankylosing spondylitis occurs predominantly in young
men with HLA-B27 (90% of cases); usually involves the
sacroiliac joints and spine; and may be associated with inflammatory bowel
Reactive arthritis is characterized by a classic
triad of conjunctivitis, urethritis, and arthritis. The arthritis
affects the ankles and knees. It affects males more than females, with onset
age 20s–30s. Onset often follows a venereal disease or bacillary dysentery.
Enteropathic arthritis occurs
in 10–20% of patients with inflammatory bowel disease.
Psoriatic arthritis affects 5–10% of patients
with psoriasis; is often a mild and slowly progressive arthritis, with
pathology similar to RA..