Seronegative spondyloarthropathies are a heterogeneous group of inflammatory diseases characterized by axial and peripheral joint involvement, enthesitis, and a high incidence of HLA-B27, but negative rheumatoid factor tests

Aetiology

• These diseases predominantly affect males aged 20-40 years old

HLA B27

• Diseases associated with the HLA B27 subtype can be remembered with the mneumonic PAIR - psoriatic arthritis, ankylosing spondylitis, IBS (+ enteropathic arthritis), reactive arthritis
• Higher prevalence in the Nothern hemisphere, especially Scandinavian countries

Shared features of the spondyloarthropathies

Shared rheumatological features

• Sacroiliac and spinal involvement
• Inflammatory arthritis - oligoarticular, asymmetric, predominantly lower limb
• Synovitis: inflammation of joint and tendon sheath linings
• Enthesitis: inflammation at sites where ligaments and tendons attach to bones e.g. Achilles tendinitis, plantar fasciitis
• Dactylitis ('sausage' digits): inflammation of the entire digit

Shared extra-articular features

• Ocular inflammation (anterior uveitis, conjunctivitis)
• Mucocutaneous lesions
• Rare aortic incompetence or heart block
• No rheumatoid nodules