What is Psoriatic Arthritis?

Psoriatic arthritis is a form of inflammatory arthritis associated with cutaneous psoriasis. The condition occurs in about 20% to 30% of patients with psoriasis, meaning that most individuals with the skin disease do not develop joint involvement. Similarly, in the vast majority of cases, the skin symptoms precede the onset of joint manifestations. More rarely, the diagnosis of cutaneous psoriasis is only made after the appearance of joint symptoms.

Psoriatic arthritis is considered part of a group of diseases known as spondyloarthropathies, which also includes ankylosing spondylitis, reactive arthritis, and arthritis associated with inflammatory bowel diseases. This group of conditions shares similar clinical features, involving both the spine and peripheral joints.

Causes

It is known that genetic, immunological, and environmental factors contribute to the disease, but the exact cause is not fully understood.

Symptoms

The most common symptom of psoriatic arthritis is joint pain, accompanied by difficulty moving the affected joint and local swelling. Typically, the pain is worse upon waking or after prolonged rest, improving with movement.

Patients often report morning stiffness, meaning difficulty moving that is worse in the morning. About two-thirds of patients have a history of cutaneous psoriasis. Some patients have involvement of a single joint, while others develop multiple joints affected at the same time, typically in an asymmetric pattern (different joints affected on the right and left sides of the body).

In addition to joint symptoms, some patients develop lower back or neck pain, also with the typical pattern of worsening upon waking. Another common manifestation of psoriatic arthritis (and other spondyloarthropathies) is tendon involvement (tendinitis and tenosynovitis) and enthesitis, which is inflammation at the site where tendons or ligaments insert into the bone.

A very characteristic sign of the disease is diffuse swelling of a finger, known as dactylitis, which gives the appearance of a “sausage digit.”

More rarely, patients with psoriatic arthritis may develop extra-articular manifestations, particularly eye inflammation.

Are there types? Which ones?

Patients with psoriatic arthritis may present with quite distinct clinical forms. Traditionally, these different presentations of the disease are classified into five subgroups:

distal arthritis: Occurs when only the distal interphalangeal joints are affected, often associated with nail psoriasis. This pattern can be mistaken for osteoarthritis
asymmetric oligoarthritis : Involves fewer than five joints in an asymmetric pattern
symmetric polyarthritis: Affects more than five joints in a symmetric pattern, which can resemble rheumatoid arthritis
axial pattern: Involves the sacroiliac joint and the spine
mutilating arthritis: A rare and very severe form of destructive arthritis

Diagnosis

The diagnosis of psoriatic arthritis is clinical, meaning it depends on a medical evaluation. Since it is a condition that can resemble several other diseases, medical knowledge and experience—typically from a rheumatologist—are essential for an accurate diagnosis.

Prevention

There are no specific preventive measures for psoriatic arthritis. However, smoking, obesity, and a sedentary lifestyle are associated with worse disease progression. Therefore, eEarly treatment (within the first few months after symptom onset) and regular medical follow-up are essential.

Treatment

Treatment for psoriatic arthritis should begin early to prevent the development of permanent joint deformities. The approach may vary depending on the extent and severity of both joint and skin symptoms. Mild cases involving only a few joints may be managed with nonsteroidal anti-inflammatory drugs (NSAIDs). However, many patients often require immunosuppressive medications. More recently, several biologic therapies have been developed and have shown proven effectiveness in treating both joint and skin manifestations.

By the Einstein Editorial Board