Prior to developing symptoms of arthritis, the majority of patients with psoriatic arthritis will already have a previous history of skin involvement with psoriasis. This may involve the scalp or occur along the edges of the hairline or over the earlobes. Also there may be involvement over the elbows and belly button area as well as over the knees. In some patients there may even be more widespread skin involvement. Patients with psoriatic arthritis will usually complain of joint pain, swelling and stiffness. There also may be a warm feeling in the joints when they are actively inflamed. The most common joints involved tend to be the end joints of the fingers (distal interphalangeal joints or DIPs), the middle joints of the fingers (proximal interphalangeal joints or PIPs), and the near joints (metacarpophalangeal joints or MCPs) as well as the wrists. Patients also will complain of pain and swelling in the toes. Some patients may have involvement that is a mirror image on each side of the body which is similar to what is seen in rheumatoid arthritis, but more commonly there is asymmetric involvement of the joints. Patients may complain of pain and stiffness in the neck and low back if they have spinal involvement present. There may be a positive family history of psoriasis in other members of the family. Men tend to have a worse form of the disease than women. More patients develop involvement of their peripheral joints in the extremities than arthritic problems in the spine. Patient may complain of low back pain which may involve their sacroiliac joints, once again in an asymmetric fashion. In one out of five patients, the arthritis may actually precede the skin involvement with psoriasis itself and this may make the diagnosis more difficult to make at that point in time. Like other forms of inflammatory arthritis, patients may note morning stiffness which can last greater than one hour and even persist throughout the day. All peripheral joints are susceptible to psoriatic arthritis along with the entire spine. Patients may note worsening of their symptoms with cold or damp weather just as in other forms of inflammatory arthritis. Patients may note pain in the heel area when there is inflammation present. They may also have involvement of the eyes with redness and pain with inflammation of the vascular portion of the eye that may occur in association with their condition.

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On physical examination one may find involvement of the skin with raised scaly lesions that may have some redness associated with them along the edges. These may be found particularly over the scalp and along the hairline as well as over the ears. They also can be found around the belly button and over the point of the elbow and over the front of the knees. With more extensive psoriasis involving the skin, this may involve much of the body as well. When one examines the nails of patients who have psoriatic arthritis along with skin involvement, then nine out of ten patients may be found to have small dug-out type lesions in the nails which is called pitting. There may be redness overlying the inflamed joints including the DIPs, PIPs and MCPs (see clinical symptoms regarding joint involvement). There may be thickening of the lining of the joints (synovitis) which produces a spongy swollen feeling on examination of the joints and the joints may at the same time be quite tender. A condition called dactylitis may be found in approximately one third of the patients with a more diffuse swelling of an entire finger or toe. The toes may appear enlarged much like a sausage and these are called "sausage shaped toes" due to the impressive swelling that may be found. Pressure on the heel may produce tenderness on examination. There may be redness found in the eye if it is inflamed due to iritis.

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Most of the time the patient's blood will show a negative rheumatoid factor result, but a small percentage of patients could have a positive rheumatoid factor in low titers. Patients may be found to have the presence of the HLA-B27 gene which does occur in association with approximately half the patients with psoriatic arthritis. Small numbers of patients may also have a positive antinuclear antibody (positive ANA). If the patient has inflammation due to widespread skin or joint involvement, then the erythrocyte sedimentation rate (ESR) may be moderately or significantly elevated. X-rays may confirm asymmetric involvement of the joints. There can be significant loss of bone over the ends of the fingers or toes due to destruction from psoriatic arthritis. If there is more marked bony destruction, then this may lead to what is classically called a "pencil-in-cup deformity." Changes may be found on x-rays of the sacroiliac joints and once again may occur in an asymmetric manner. Sometimes there is actual joining together or fusion of the bones in the hands or feet. There also may be seen a whitish appearance along the edge of the bone due to reactive type changes in what is called the periosteum producing this periosteal reaction.

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The diagnosis of psoriatic arthritis is made more easily with the presence of the typical psoriasis skin lesions over the scalp and skin with pitting of the nails occurring in conjunction with arthritis of the peripheral joints and spine. The diagnosis may be more difficult in the presence of arthritis alone where the skin findings of psoriasis have not yet occurred. There are multiple ways that psoriatic arthritis may present itself. It may mimic rheumatoid arthritis with symmetric involvement of the joints or may present with involvement of primarily the distal joints of the hands and feet. More commonly it involves multiple joints in the hands and feet including the DIPs, PIPs and MCPs as well as the wrists in the upper extremities, and the DIPs, PIPs and MTPs in the feet with asymmetric type involvement. There also may be involvement of the spine in up to 40% of individuals. This may actually occur later on in the disease process. Very rarely, an individual may develop a destructive form of arthritis called arthritis mutilans with aggressive destruction of the bones in the fingers and toes. Patients may switch amongst these various types of presentations from one type to another. Patients also may be diagnosed on the basis of changes that occur in the spine including the cervical, thoracic or lumbar spine and particularly with asymmetric involvement of the sacroiliac joints. In a situation where a patient has a significantly positive rheumatoid factor lab result present, then it raises the issue of whether the patient simply has the coincidence of rheumatoid arthritis and cutaneous (skin) psoriasis which are both common conditions, rather than psoriatic arthritis. Also the same dilemma arises in a patient who just has involvement of the end joints of the fingers alone (DIPs), because this could be the coincidence of osteoarthritis plus cutaneous psoriasis which are also two common illnesses. If there is more marked redness and swelling with signs of inflammation present, then this might be more suggestive of psoriatic arthritis and x-ray findings of more aggressive destructive changes in the end joints might help to confirm this.

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The most common initial approach to the treatment of psoriatic arthritis involves the use of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) to control the pain, inflammation and stiffness from psoriatic arthritis. It is important also to control the inflammation and involvement present in the skin itself as there is some evidence that decreasing the activity in the skin will quiet down flares in the peripheral joints. Conversely with any flare-ups of the scalp and skin, there tends to be a flare of the arthritis. The skin and scalp are treated with steroid creams, lotions or shampoos as well as tar based products. Dermatologists also may choose to use Psoralen plus UV light therapy (PUVA). If a patient's arthritis cannot be controlled with these measures, then he or she they may need to be treated as well with Disease Modifying Anti-Rheumatic Drugs (DMARDs). Methotrexate has had a long history of usage for the skin, and now in recent years for the joints as well. Previous studies have shown that injectable gold therapy also may work to control psoriatic arthritis and does so as successfully as it works in rheumatoid arthritis. Plaquenil as an antimalarial form of therapy was shunned for a period of time because of concern about the possibility of flaring the rash of psoriasis, but more recent studies have shown that it may be used safely to treat psoriatic arthritis. Azulfidine is another alternative DMARD which has had success. Cyclosporine is another option for treatment, but needs close follow-up due to the difficulty administering this medication without causing significant side effects. Recently there have been exciting results when using tumor necrosis factor (TNF) inhibitors in the treatment of psoriatic arthritis. Enbrel (etanercept) has been approved for use in psoriatic arthritis. This is given by sub-cutaneous injection twice weekly (self-injected). Another TNF inhibitor, Remicade (infliximab), is given intravenously every two months. It still, however, is awaiting FDA approval for use in psoriatic arthritis patients.

Joel E. Rutstein, M. D.