Special features

Psoriasis arthritis — clinical features and diagnosis

By Alan Worsley, MRPharmS, PhD, Fraser Birrell, PhD, FRCP, and Richard Copeland, MPhil, MRPharmS

Psoriatic arthritis is an inflammatory joint disease associated with arthritis. This article, the first in a special feature about the disease, describes its clinical features and symptoms, its classification and its diagnosis

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Clinical features of psoriatic arthritis

Alan Worsley is a senior lecturer in pharmacy practice at the University of Sunderland

Fraser Birrell is a consultant rheumatologist

and Richard Copeland is a specialist pharmacist in rheumatology

both at Northumbria Healthcare NHS Foundation Trust

Antonia Reeve/SPL

Coloured X-ray showing an arthritic elbow joint

SUMMARY

Psoriatic arthritis (PsA) is an inflammatory joint disease associated with psoriasis. The first reported association between psoriasis and arthritis was documented in 1818 and a number of reports of patients in whom skin and joint disease were thought to be coincidental were cited by other researchers, until the term psoriatic arthritis was introduced in 1959.

In 1964 the American Rheumatism Association classified PsA as distinct from other rheumatic conditions.

Following recognition of PsA as a separate disease entity, it was included in the group of seronegative spondyloarthropathies — a family of inflammatory rheumatic diseases that affect the spine, joints, ligaments and tendons.

Other diseases in this group include enteropathic arthritis (eg, associated with Crohn’s disease or ulcerative colitis), ankylosing spondylitis and reactive arthritis or Reiter’s disease.

Clinical features of psoriatic arthritis

Patients with PsA may suffer from the following features at different stages of their disease:

• Any of the five classic patterns of joint involvement, described by Moll and Wright (these may coexist)

• Inflammatory DIP joint involvement

• Peripheral polyathritis (often symmetrical as seen in rheumatoid arthritis)

• Spondylitis and sacro-ilitis (inflammation of the spine and sacro-iliac joints)

• Asymmetrical oligoarthritis

• Arthritis mutilans (characterised by destruction and “telescoping” of the fingers)

Any of these may be accompanied by:

• Any form of psoriasis (or a personal or family history of psoriasis)

• Dactylitis (sausage-like digits)

• Enthesitis

• Tenosynovitis