Are Psoriasis and Psoriatic Arthritis the Same?

Not every person with psoriasis gets psoriatic arthritis. The condition affects about one-third (almost 30 percent) of the people with psoriasis. Studies report that having severe psoriasis symptoms or nail psoriasis generally increases the risk of psoriatic arthritis. About 90 percent of people with psoriatic arthritis have nail psoriasis.

Many people with psoriatic arthritis initially have skin lesions of psoriasis. Nonetheless, psoriatic arthritis can occur in people with no skin signs of psoriasis. Furthermore, the joint affected may not coincide with the site where skin lesions are present.

• For example, you may have psoriatic arthritis that affects the knee but no psoriatic skin lesions over the legs or knee.
• Similarly, you may have psoriatic plaques over the elbow but no involvement of the elbow joint.

Symptoms of psoriasis may vary depending on the type of psoriasis (such as plaque-type, guttate, or pustular psoriasis).

• Psoriasis vulgaris or plaque-type psoriasis is the most common type of psoriasis, accounting for about 80 percent of psoriasis cases. It usually affects the skin over the scalp, elbows, and knees, although it can involve any part of the body such as the face, palms, soles, and back.
• Lesions are generally symmetrical and are called plaques. A plaque is an area of red, thickened skin with silvery scales. The silvery scales may be absent in skin folds (flexural psoriasis) such as in the groin, buttocks, or under the breasts. In such sites, the lesions tend to have a shiny appearance and moist peeling surface.
• The lesions may cause minimal to severe itching. Severe itching may cause repeated scratching that leads to skin thickening giving it a leathery appearance called lichenification. The skin may become irritated, dry, and cracked with a tendency to bleed.

Nail involvement is seen in about 35 to 50 percent of people with psoriasis. Nail psoriasis can present as pitted, brittle, deformed nails. The nails may develop ridges, become fragile, and even crumble or separate from the nail bed. Nail psoriasis has a strong association with psoriatic arthritis. 

People with psoriatic arthritis may or may not have skin lesions. They have a high likelihood of having typical psoriatic nail lesions. Besides skin and nail signs, people with psoriatic arthritis may report these symptoms:

• Joint pain and tenderness
• Asymmetric arthritis (for example, one elbow joint may have symptoms, whereas the other may be completely fine)
• Joint swelling
• Joint stiffness or reduced range of motion typically in the morning or after periods of inactivity
• Sausage-like swollen toes and fingers
• Low back pain

Besides skin and nail changes, there may be other extraarticular (outside the joint) manifestations of psoriatic arthritis that include:

• Fatigue
• Blurring of vision
• Eye pain or redness
• Urogenital involvement (such as inflammation of the vagina, cervix, urethra, penis, or prostate gland)
• Involvement of the gut, heart, and liver

When left untreated, psoriatic arthritis can lead to severe joint involvement, causing permanent joint deformity known as arthritis mutilans. Moreover, it can increase the risk of other chronic conditions such as heart diseases, high blood pressure, and diabetes.

Psoriasis and psoriatic arthritis are chronic conditions that cannot be cured. Treatment, however, can help manage symptoms and prevent disease progression and the development of complications.

Treatment is generally determined by the severity of the condition and type of psoriasis. Psoriasis treatment may include:

• Corticosteroids
• Phototherapy
• Biologic agents
• Vitamin D analogs
• Tar-based products
• Topical retinoids
• Cyclosporine
• Acitretin
• Methotrexate

Treatment of psoriatic arthritis generally includes:

• Nonsteroidal anti-inflammatory drugs such as ibuprofen and naproxen
• Disease-modifying antirheumatic drugs such as sulfasalazine, methotrexate, and leflunomide
• Biologic agents such as adalimumab, certolizumab, and etanercept
• Janus kinase inhibitors such as tofacitinib
• Phosphodiesterase-4 inhibitors such as apremilast
• Intraarticular (injected into the joint) steroid injections
• Physical therapy
• Surgery such as total joint replacement