Seronegative arthritis describes a group of conditions that present with inflammatory arthritis but without a positive rheumatoid factor, hence seronegative.

Spondyloarthropathies, crystalline and viral arthropathies, and rheumatoid arthritis are the most common diagnoses in these patients.

Differential diagnosis:

• Psoriatic arthritis
• IBD arthritis
• Reactive arthritis
• Ankylosing Spondylitis
• Enteropathic arthritis
• Behcet's disease (resembles other spondyloarthropathies in certain respects but in other ways is quite distinct. It is associated with HLA-B51 rather than HLA-B27.)

Features

The predominant features are:

• Axial involvement
• Peripheral joint involvement- predominantly asymmetrical and in lower extremities
• Enthesitis (inflammation at site where tendons and ligaments insert to bone - may manifest as Achilles tendonitis for example)
• High incidence of HLA-B27 but negative rheumatoid factor tests

The unifying features of the spondyloarthropathies is inflammation involving entheses: enthesopathy. This is strongly associated with HLA-B27.

Key symptoms