Psoriatic arthritis a form of inflammatory arthritis that occurs with psoriasis, a skin condition that shows up as a red scaly, sometime itchy rash that typically occurs over the knees, elbows and scalp, but can occur anywhere on the body including the inside of the ears, groins and buttock creases. It can also cause changes to the nail itself.
The disease can affect large joints as well as the distal small joints in the hands or feet, and may cause complete swelling of a finger or toe, a condition that is also called dactylitis. (A diagnosis of psoriasis refers only to the skin disease.) People with psoriatic arthritis can also have spinal inflammation.