Symptoms of Psoriatic Arthritis

Psoriatic arthritis is an inflammatory form of arthritis integrally linked to psoriasis. It typically develops in adults 30 to 50 but can start as early as childhood. Men and women are equally affected.

Psoriatic arthritis occurs as a direct consequence of psoriasis. As an autoimmune disease, psoriasis causes inflammation when the immune system suddenly attacks normal cells in the outer layer of skin (called the epidermis). The inflammation has a spill-over effect, eventually impacting other cells and tissues. Over time, this can trigger pain and stiffness in the joints, leading to the development of psoriatic arthritis.

It is important to recognize the signs and symptoms of psoriatic arthritis so that a doctor can diagnose the disease and start treatment as soon as possible.

It is even possible to have psoriatic arthritis with no skin involvement at all.

Psoriatic arthritis symptoms vary from person to person. They tend to develop in episodes, known as flares, in which symptoms suddenly appear and just as suddenly resolve.

Unlike psoriasis, in which the immune system directly attack skin cells, psoriasis arthritis is caused almost entirely by inflammation. Common symptoms include:

• Pain and swelling in one or more joints, typically the wrists, knees, ankles, fingers, toes, and lower back
• Swelling of the fingers and toes, known as dactylitis, resulting in a thick, sausage-like appearance
• Morning stiffness, similar to osteoarthritis
• Silvery-white skin lesions, known as plaques, often on the scalp, elbows, knees, and lower spine
• Pitting or lifting of the nails, also referred to as nail dystrophy
• Persistent fatigue, common with chronic inflammatory diseases
• Eye problems, including uveitis and conjunctivitis ("pink eye")

There are five subtypes of psoriatic arthritis, each of which is characterized by its location and severity. It is not uncommon for a person to switch from one subtype to another. Scientists are unsure why this is but believe that certain environmental triggers can alter the already-abnormal immune response.

The changes in subtype also reflect the progressive nature of the disease. As certain joints sustain damage, often irreversible, the inflammatory response may simply broaden and affect other joints in the body.

Moreover, it is possible to have multiple subtypes or to develop other forms of arthritis, both autoimmune and non-autoimmune.

Asymmetric Psoriatic Arthritis

Psoriatic arthritis is asymmetric when a joint is affected on only one side of the body. Asymmetric psoriatic arthritis tends to be milder than other forms of the disease and is often the first type experienced. According to a 2013 review in the Polish Journal of Radiology asymmetric psoriatic arthritis accounts for roughly 70 percent of all cases.

Symmetric Psoriatic Arthritis

Symmetric psoriatic arthritis, as per its name, is characterized by pain and swelling in the same joints on both sides of the body. Fingers and toes are typically affected as well as larger joints of the hips and knees.

Symmetrical psoriatic arthritis accounts for around 15 percent of all cases. It is often preceded by asymmetric disease but may develop symmetrically from the start.

Distal Interphalangeal Predominant (DIP) Psoriatic Arthritis

Distal interphalangeal predominant (DIP) psoriatic arthritis may sound complicated, but it simply means that the distal (near the nail) joints of the phalanges (fingers or toes) are affected.

This type of psoriatic arthritis is characterized by pain and stiffness near the tips of the fingers or toes. When viewed on an X-ray, the ends of the bone will often appear narrowed like a pencil tip, while the adjacent joint will have a compressed, cup-like appearance.

Nail changes, including pitting, thickening, and lifting (onycholysis), are also common.

Arthritis Mutilans

Arthritis mutilans is an uncommon but severe form of psoriatic arthritis. It is characterized by a condition called enthesitis in which the tissues connecting tendons and ligaments to bone become inflamed. Arthritis mutilans is believed to affect around 5 percent of people with psoriatic arthritis.

The aggressive nature of the disease can cause bone resorption (the breakdown of bone tissue), cartilage loss, and joint deformity.

Psoriatic Spondylitis

Spondylitis refers to inflammation of the spinal column. Only around 5 percent of people with psoriatic arthritis will have spondylitis as their main symptom. Although the spine is less commonly affected by psoriatic arthritis than other joints, while stiffness in the neck, lower back, or pelvis is known to occur more frequently.

Another common denominator is the genetic marker human leukocyte antigen B27 (HLA-B27), which is present in over half of the people with psoriatic spondylitis.

As a general rule, you should suspect psoriatic arthritis if you have symptoms of psoriasis or a family history of autoimmune diseases. At the same time, it is not uncommon to have multiple autoimmune disorders given that the diseases often share the same genetic mutations.

If you develop symptoms of psoriatic arthritis, ask your doctor for a referral to a joint specialist known as a rheumatologist.

While many internists are capable of managing mild psoriasis, psoriatic arthritis is a far more complicated disease. It is not only more difficult to diagnose but often requires a combination of drugs, including disease-modifying antirheumatic drugs (DMARDs) like methotrexate and newer-generation biologic drugs like Enbrel (etanercept) and Humira (adalimumab).