Psoriatic arthritis overview
Psoriasis is a skin disease. In psoriasis, basic lesion is in skin. As skin has largest area, the involvement of psoriasis goes extensive. Eventually it manages to attack nail, bones, joints and genital organ. Its complications are also severe. When psoriatic attack happens to occur in bones and joints it is called psoriatic arthritis. Psoriatic arthritis is a joint disease where psoriasis is primary pathology and cause inflammation of joints. Usually rheumatoid factor is negative in psoriatic arthritis. Therefore, it is called sero-negative spondylo-arthropathy. Previously presentations of this disease were thought to be due to rheumatoid arthritis occurring coincidentally with psoriasis. Psoriatic arthritis often erodes the joints and cause severe disability to the patient. When we want to diagnose psoriatic arthritis by symptoms, a lot of confusion arises there. This disease often has presentations similar to other related diseases. Treatment of psoriasis is also very difficult. If we try to remove the disease, side effects of drugs brings another problem. Another obstacle in front of us arises in the form of complications. Therefore, we need to be vigilant about every possible corner of the psoriatic arthritis treatment.
7–20% of patients with psoriasis may develop psoriatic arthritis. Up to 0.6% of the population, potentially not having psoriasis may develop psoriatic arthritis. The occurrences of psoriatic arthritis are mostly between the age of 25 and 40 years. Most patients develop psoriasis before psoriatic arthritis. However, many few, up to 20% gets psoriatic arthritis first. On the other hand, many have both diseases simultaneously.
Symptoms of psoriatic arthritis
Skin manifestations: Most patients will have psoriasis first. Therefore, they have or have history of typical psoriatic lesions. Psoriasis is a common recurrent inflammatory disease of the skin and it usually turns to chronic one. The typical lesions of psoriasis are circumscribed, red, dry and having onion peel like scales. They may be of various sizes. Usually they are flat elevations of skin greater than 1 centimeter. The scales are usually silvery white in color. The lesions have a tendency to choose the scalp, nails, extensor surfaces of the arm, forearm, hand, hips, legs and foots, umbilical region, and sacrum respectively for attack. Affected nail shows pitting, breaking of nail in fragments, erosion, hyperkeratosis below nail and horizontal ridging. Some patients may be unaware or may develop psoriasis later.
Joint manifestation: The first symptom of psoriatic arthritis may be pain and swelling of the joints and pain in soft tissue of limb and tendons. This joint pain may have intermittent exacerbation followed by complete or near complete pain free intervals. Commonly destructive arthritis and disability do not occur. The followings are the patterns of joint involvement.
- Asymmetrical inflammatory arthritis involving 2-4 joints: The patients feel tightness, pain and stiffness in joints in early morning, which improve with daily activities. About 40% of patients are affected by such condition. Many present with a combination of inflammation of joint and inflammation around joints. This occurs most characteristically in the hands and feet are involved. When inflammation of a finger or toe is present tendon inflammation and inflammation of intervening tissue produce a sausage like condition in digit which is called dactylitis. Large joints, such as the knee and ankle, may also be involved. Sometimes they are inflamed with very large effusions.
- Symmetrical arthritis of >5 joints: This feature is more likely in rheumatoid arthritis but may occur in about 25% of cases of psoriatic arthritis. It is predominant in women and has symmetrical involvement of small and large joints in both upper and lower limbs. Nodules are absent or less prominent and other features other than joint of rheumatoid arthritis are absent. Arthritis is generally less extensive and more benign in psoriatic arthritis. Here, hand
deformity often results from tendon inflammation and soft tissue contractures.
- Distal finger joint arthritis: It is a rare happening but if it is present, it is characteristic. This pattern affects men more often than women. It also targets tissues surrounding the finger joints. Almost all cases have nail dystrophy along with joint feature.
- Psoriatic spondylitis: Like ankylosing spondylitis, it may also present with back pain.
- Arthritis mutilans: Here, erosion of the targeted joints, fingers and toes mainly, occur. This occurs in less than 5% of cases of psoriatic arthritis. Prominent cartilage and bone destruction in those joint cause marked instability in those joints.
Types of psoriatic arthritis
Five clinical patterns of psoriatic arthritis occur:
- Asymmetrical distal inter phalanges joint involvement with nail damage (16%)
- Arthritis mutilans with erosion of phalanges and metacarpals (5%)
- Symmetrical poly-arthritis like rheumatoid arthritis, with claw hands (15%)
- Oligo-arthritis with swelling and tendon involvement of one or a few hand joints (70%)
- Ankylosing spondylitis like symptoms only or with symptoms of peripheral arthritis (5%)
Diagnosis of psoriatic arthritis
Diagnostic Criteria for proper diagnosis of Psoriatic Arthritis
Diagnosis of psoriatic arthritis is always a bit troublesome. No test can detect psoriatic arthritis directly. We depend on exclusion. Rheumatoid arthritis and other inflammatory arthritis must be excluded to diagnose psoriatic arthritis. If the patient has or has history of psoriasis with joint involvement, we can say for sure it is psoriatic arthritis. To exclude other diseases and diagnose it correctly many diagnostic criteria has been proposed. Here, we show you simple criteria.
According to these diagnostic criteria, psoriatic arthritis is diagnosed when there is inflammatory disease of joint, spine, or tendon with ≥3 points from the following points:
1. Evidence of psoriasis (any one of a, b or c)
a. Active psoriasis: presence of psoriatic lesion in skin at present, judged by a rheumatologist or dermatologist
b. Previous history of active psoriasis: patient or his/ her family physician, his/her dermatologist, his/her rheumatologist, or any other qualified health care provider by whom he/she was treated or diagnosed can give a previous history of psoriasis.
c. History of psoriasis in a first-degree or second-degree relative is also significant.
2. Psoriatic type nail dystrophy: typical nail dystrophy, as described above may be confirmatory of psoriatic arthritis.
3. Negative finding for rheumatoid factor: negative test for rheumatoid factor is a predictor in this disease.
4. Dactylitis (any one of a or b)
a. Typical swelling of an entire digit
b. Previous history of dactylitis reported by rheumatologist
5. Radiologic evidence of new bone formation near joint: ill-defined ossification of near joint margins on plain x-rays of hand or foot. Often ossification of bones near vertebral bones is seen. There might be radiological evidence of erosion of terminal hand joint tufts. Tapering or whittling of phalanges or metacarpals is another sign in radiology. Cupping of proximal ends of phalanges is also seen in some reports. Bony ankylosis and erosion of metatarsals is also found. These changes have predilection for distal inter phalange joints and proximal inter phalange joints.
Treatment of psoriatic arthritis
- NSAIDs: for controlling mild disease
- DMARDs: The patients not responding to NSAIDs and exercise, are given DMARDs. Methotrexate, sulfasalazine, ciclosporin and leflnomide can be chosen. Methotrexate is our first choice because it will help the skin lesions also. Others are also effective.
- Biological agents: Anti-TNF therapy like adalimumab help arthritis but it has more effect on skin, nail, tendon and dactilitis. Alefacept, efalizumab is also found effective controlling both psoriasis and arthritis.
- The retinoid acitretin is a effective treatment for skin lesions and arthritis. Methoxypsoralen and long wave ultraviolet light is a photo-chemotherapy used for skin lesions in psoriasis. It can also help exacerbations of inflammatory arthritis.
- Systemic steroid is of no use in psoriatic arthritis treatment. Intra-articular steroid may help the joints.
- Other assistive techniques may help reduce pain and reducing disability.