Psoriatic arthritis and synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome.

Psoriatic arthritis is an inflammatory arthropathy associated with psoriasis, and its clinical presentation varies from case to case. Distal interphalangeal involvement is characteristic but not seen in all patients. Enthesopathy, including that of the spine, is common and contributes to the classification of psoriatic arthritis as a seronegative spondyloarthropathy. The etiopathogenesis of psoriatic arthritis is not well understood, and evolution as measured by follow-up is variable. Treatment includes nonsteroidal anti-inflammatory drugs and some of the drugs used in the treatment of rheumatoid arthritis. Sulfasalazine and, in the more severe cases, cyclosporine, are being studied for efficacy and tolerance. Some cases of psoriatic arthritis are associated with an inflammatory bone disease, frequently seen on the anterior chest wall, which is part of the newly described SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome. SAPHO syndrome is characterized by this bone involvement, which can affect the spine and peripheral bones. Various skin conditions are associated with this syndrome, but they do not necessarily occur in all cases. Chronic recurrent multifocal osteomyelitis, which is seen mostly in children, may be a presentation of SAPHO syndrome. Associations with sacroiliitis, bowel disease, and psoriasis link SAPHO syndrome with the spondyloarthropathies.