Reactive arthritis is characterized by a classic triad of conjunctivitis, urethritis, and arthritis.
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 disease.
Reactive arthritis is characterized by a classic triad of conjunctivitis, urethritis, and arthritis. 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 mild and slowly progressive arthritis, with pathology similar to RA.