Psoriatic arthritis is defined as psoriasis combined with arthritis. This disease differs from rheumatoid arthritis on the basis of the pattern of arthritis involvement, rheumatoid factor negativity, and roentgenographic feature. Psoriatic arthritis is classified as a seronegative spondyloarthropathy because this disease have sacroilitis and spondylitis or Reiter's syndrom.

This is a case report of psoriatic arthritis which is the spondyloarthropathy combined with pustular psoriatic lesion.