Psoriatic arthritis is a specific type of arthritis that develops in approximately 23 percent of people who have psoriasis. The disease can be difficult to diagnose, particularly in its milder forms. Psoriatic arthritis can start slowly with mild symptoms, or it can develop quickly. Left untreated, psoriatic arthritis can be a progressively disabling disease.

Symptoms include:

• Stiffness, pain, swelling and tenderness of the joints and the soft tissue around them
• Reduced range of motion
• Morning stiffness and tiredness
• Nail changes, including pitting or lifting of the nail—found in 80 percent of people with psoriatic arthritis
• Redness and pain of the eye, such as conjunctivitis Joints commonly affected by psoriatic arthritis are the wrists, knees, ankles, lower back and neck. Psoriatic arthritis can develop any time, but for most people it appears between the ages of 30 and 50, and it affects men and women equally.

Symmetric Arthritis
This form of Psoriatic Arthritis is much like rheumatoid arthritis but generally milder with less deformity. It usually affects multiple symmetric pairs of joints and can be disabling. The associated psoriasis is often severe. About 50 percent of people with this form of PA will develop varying degrees of progressive, destructive disease, which can be disabling.

Asymmetric Arthritis
Asymmetric (not occuring in the same joints on both sides of the body) arthritis usually involves only one to three joints. It can affect any joint, such as the knee, hip, ankle or wrist. It could involve just one finger or a number of them. The hands and feet have enlarged "sausage" digits, caused by swelling and inflammation of tendons. The joints may be warm, tender and red. Individuals may experience periodic joint pain that is usually responsive to medical therapy. This form is generally mild, although some people will develop disabling disease.

Distal Interphalangeal Predominant
This form of arthritis, although the "classic" type, occurs in only about 5 percent of people with psoriatic arthritis. Primarily, it involves the distal joints of the fingers and toes (the joint closest to the nail). Sometimes it is confused with osteoarthritis, but nail changes are usually prominent.

Spondylitis
In about 5 percent of individuals, inflammation of the spinal column is the predominant symptom. Inflammation with stiffness of the neck, lower back, sacroiliac or spinal vertebrae are common symptoms in a larger number of patients, making motion painful and dificult. Peripheral disease can be present in the hands, arms, hips, legs and feet. Spondylitis, when severe, may be associated with generalized symptoms.

Arthritis Mutilans
This is a severe, deforming and destructive arthritis that affects fewer than 5 percent of people with psoriatic arthritis. It principally affects the small joints of the hands and feet, though there is frequently associated neck or lower back pain. This type can progress over months and years. Arthritic flares and remissions tend to coincide with skin flares and remissions.