Psoriatic arthritis is a chronic inflammatory arthritis associated with the skin disease psoriasis. soriasis, which affects about 2 percent of the U.S. population, most often causes patches of thick, reddened, irritated skin with flaky, silver-white patches called scales.
Psoriatic arthritis affects about 10% of patients with psoriasis. It typically appears about 10 years after the onset of psoriasis, which can manifest at any age, though most people are diagnosed between the ages of 15 and 35. Abnormalities of the fingernails and toenails in patients with psoriasis increase the likelihood that they will develop the arthritic form of the disease. Psoriasis and psoriatic arthritis are thought to be an inherited condition.
Symptoms include painful, swollen joints, back pain, and tenderness where muscles or ligaments attach to bones, particularly the heel and bottom of the foot. Nail changes, including a nail pitting and separation from the nail bed can also be seen. Patients also can experience generalized fatigue, decreased range of motion and redness of the eyes (conjunctivitis).
There are five types of psoriatic arthritis. Each type has a distinctive pattern of joint involvement, but all types have associated skin disease.
Symmetric psoriatic arthritis. Presents much like rheumatoid arthritis – characterized by joint swelling, pain and stiffness, but generally milder with less deformity. It usually occurs in the same joints on both sides of the body and can cause life-long diability if left untreated.
Asymmetric psoriatic arthritis This can involve a few or many joints anywhere on the body. It typically affects larger joints, such as the knee, hip, ankle or wrist. Some people may develop a painful, sausage-like swelling of the fingers and/or toes called dactylitis. This form is generally mild, although some people might develop disabling disease.
Distal interphalangeal predominant. This form occurs in only about 5 percent of people who have the disease. It usually involves the distal joints of the fingers and toes (those joints closest to the nail). This form of the disease often involves changes in the nails, including pitting, splitting or degeneration.
Psoriatic Spondylitis. – This type is characterized by inflammation of the spinal column and occurs in about 5% of patients with psoriatic arthritis.
Arthritis mutilans. This is is a severe, deforming and destructive condition that is the rarest type of psoriatic arthritis. It is characterized by resorption of bones and the consequent collapse of soft tissue.
Psoriatic arthritis is a seronegative spondyloarthropathy. It is diagnosed through physical examination, x-rays and laboratory tests. Lab test abnormalities seen include a negative rheumatoid factor and and the presence of HLA-B27. One must have the skin changes of psoriasis before a diagnosis can be made. Treatment focuses on medications to relieve the inflammation, including NSAIDs, sulfasalazine, methotrexate and TNF-alpha blockers.