Dactylitis: pathogenesis and clinical considerations.

Dactylitis is considered a hallmark feature of psoriatic arthritis (PsA), but it is found in other spondyloarthropathies, especially reactive arthritis, and other conditions (eg, sarcoidosis, gout, sickle cell disease, and a variety of infections). Dactylitis is difficult to define and assess with any level of consensus and consistency in PsA. A new objective measure has been developed to make assessment more uniform for clinical trials. The underlying pathophysiology has also been difficult to determine in spondyloarthropathy: synovitis, tenosynovitis, and enthesitis have all been recognized. The pathophysiology in other conditions varies but usually involves soft tissue and sometimes involves bone or joint. In non-spondyloarthropathies,treatment is determined by the underlying cause. Research on dactylitis treatment in PsA suffers from a paucity of trials and inconsistent outcome measurement. The only drug with good evidence of benefit from randomized controlled trials thus far is infliximab.