Other seronegative spondyloarthropathies

Seronegative spondyloarthropathies are a group of overlapping forms of inflammatory joint disease, the most common conditions being psoriatic arthritis and ankylosing spondylitis. Other less common conditions include reactive arthritis, enteropathic arthritis and SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis). Shared features include a propensity to affect the spine, an association with anterior uveitis, involvement of the enthesis, the absence of rheumatoid factor and an increased frequency of HLA-B27. Psoriatic arthritis has several distinctive characteristics that may vary from patient to patient and include frequent involvement of distal interphalangeal joints, dactylitis, new bone formation within the enthesis, osteolysis and ankylosis. Genetic factors are important, with HLA-Cw06-containing haplotypes associated with psoriasis and peripheral joint inflammation, and HLA-B27 variants associated with axial involvement, especially sacroiliitis. Psoriatic arthritis patients are managed with physical and occupational therapy, NSAIDs, non-biological disease-modifying anti-rheumatic drugs and local corticosteroid injections. The advent of tumour necrosis factor-α inhibitors has provided an important new dimension to treatment options for those with severe or persistently active disease, and new therapeutic agents are currently in advanced phases of clinical trials.