Other seronegative spondyloarthropathies

Seronegative spondyloarthropathies are a group of overlapping forms of inflammatory joint disease, the most common conditions being ankylosing spondylitis and psoriatic arthritis. Other less common conditions include reactive arthritis, enteropathic arthritis and SAPHO (synovitis, acne, pustolosis, hyperostosis, osteitis). Shared features include a propensity to affect the spine, an association with anterior uveitis and HLA-B27, involvement of the enthesis, and the absence of rheumatoid factor. 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-CW6 containing haplotypes associated with psoriasis and peripheral joint inflammation and HLA-B27 associated with axial involvement especially sacroiliitis. The advent of anti-TNF antagonists provides an important new dimension to treatment options for those with progressive disease.