Psoriatic Arthritis: What It Is and How It Relates to Psoriasis

Psoriatic arthritis is inflammation of the joints that develops in some people with psoriasis. Below is how the disease manifests, how it differs from rheumatoid arthritis, and what questions to bring to a rheumatologist.

What psoriatic arthritis is

It is a long-term condition in which joints hurt, swell, and lose mobility. The small joints are most often affected — the interphalangeal joints of the hands and feet, as well as the spine and sacroiliac joints. The disease can be mild, but sometimes it is serious and can involve many joints; in rare cases, joint destruction and finger deformity are possible (mutilans form, about 7% of patients). Psoriasis occurs in 2–3% of people, and arthritis develops in 13.5–47% of them; it most often begins at age 20–50, equally often in men and women.

How psoriasis is related to joint involvement

Both conditions are driven by the immune system attacking the body's own healthy tissue. Why the joints become inflamed in one person with psoriasis and not in another is still unknown; genetic, immunological, and environmental factors are thought to contribute. Arthritis can appear many years after the first skin rash. The skin and joints are far from always flaring at the same time.

Main manifestations of the disease

Symptoms are worse in the morning and may ease with activity. The set of signs is as follows:

• pain, swelling, and stiffness in one or more joints;
• sausage-shaped fingers — firm swelling that changes the shape of the finger;
• nail changes: different color, pitting, and pits;
• feeling run down, loss of energy;
• inflammatory back pain when the spine is involved.

Skin manifestations also occur at the same time — dry, scaly patches.

Can arthritis occur without psoriasis

Skin and joint manifestations do not always appear at the same time; evaluation is needed even with clear skin. Recurring pain and swelling are a reason to see a doctor, even if there is no psoriasis. The onset of the disease most often occurs at age 20–50, although particularly severe variants occur in young men. If a child has joint pain, a doctor should be seen.

How it differs from rheumatoid arthritis

The patterns of inflammatory arthritis differ. In psoriatic arthritis, asymmetric involvement of several joints (knees, wrists, ankles, elbows) is more common — this variant has been described in 70% of patients. The rheumatoid-like form, symmetric as in rheumatoid arthritis, occurs in 15–20%. Isolated involvement of the distal interphalangeal joints occurs in 5%. A pattern resembling ankylosing spondylitis also occurs, and isolated inflammation of the spine occurs in 2–4% of cases. A separate sign is dactylitis, inflammation of the entire finger. The disease is differentiated from rheumatoid arthritis, reactive arthritis, ankylosing spondylitis, osteoarthritis, and gout.

How the diagnosis is made and when to see a rheumatologist

The doctor examines the joints, nails, and skin and orders blood tests and, if necessary, joint fluid analysis, X-rays, ultrasound, or MRI. The diagnosis is made using the CASPAR criteria: signs of inflammatory joint involvement are required — arthritis, spondylitis, or enthesitis — and at least 3 points from five categories. Seeing a doctor (including a rheumatologist) makes sense if pain, swelling, and stiffness recur, even when the skin is not involved.

Psoriatic arthritis by itself is not a reason to call an ambulance. Numbers 103 or 112 are needed if life-threatening signs appear: severe chest pain, signs of stroke, severe injury.

A calm conversation with a doctor about an evaluation plan is more useful than any article — including this one: the material is for reference and does not replace a consultation.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer