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Conditions · Rheumatology

Psoriatic arthritis !

An inflammatory arthritis linked to psoriasis that can swell whole fingers, damage end joints and affect the spine and tendons.

Updated 2026-11-01

Structures involved

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In the clinical exam

Why it happens

What it is

A chronic inflammatory arthritis of the spondyloarthritis family that occurs in people with psoriasis or a family history of it. It can involve peripheral joints, the spine, entheses, digits (dactylitis) and nails.

Who gets it

Develops in roughly one in five people with psoriasis, usually aged 30 to 50 and equally in men and women. In most cases skin psoriasis appears years before the arthritis. It is seen in Colombia and the rest of Latin America, where it is often underdiagnosed among dermatology patients.

Causes

  • Immune-mediated; cause unknown
  • Genetic predisposition (HLA-B27 in axial disease, HLA-C*06 with psoriasis)
  • Possible triggers: joint trauma (deep Koebner phenomenon), infections, obesity

Risk factors

  • Psoriasis, especially severe, scalp, intergluteal or nail psoriasis
  • Family history of psoriasis or psoriatic arthritis
  • Obesity
  • Smoking

Pathophysiology

The IL-23/IL-17 axis and TNF drive inflammation that starts at entheses (tendon and ligament insertions) and spreads to synovium and bone. The disease both erodes bone and forms new bone, giving the typical pencil-in-cup deformity of distal joints, periostitis and spinal syndesmophytes. Nail disease reflects inflammation at the nail–enthesis complex of the distal phalanx.

Classification

  • Asymmetric oligoarthritis (4 or fewer joints)
  • Symmetric polyarthritis (rheumatoid-like)
  • Distal interphalangeal-predominant arthritis
  • Axial spondyloarthritis (sacroiliitis, spondylitis)
  • Arthritis mutilans (severe destructive form)

Symptoms and signs

  • Pain, swelling and morning stiffness of joints, often asymmetric
  • Involvement of the distal finger joints next to nail changes
  • Whole swollen sausage-like fingers or toes (dactylitis)
  • Heel pain from Achilles or plantar fascia enthesitis
  • Inflammatory back pain that improves with exercise
  • Nail pitting, onycholysis and skin plaques of psoriasis
  • Fatigue; red, painful eye (uveitis)

Diagnosis

Clinical
Inflammatory arthritis, enthesitis or spinal disease plus psoriasis (current, past or family), nail dystrophy, dactylitis and negative rheumatoid factor, as weighted in the CASPAR classification criteria.
Tests
No specific test. ESR and CRP may be normal or high; rheumatoid factor and anti-CCP are usually negative; HLA-B27 in axial disease. Uric acid may be raised, so joint fluid analysis helps exclude gout. Screening for tuberculosis and hepatitis before biologics.
Imaging
Radiographs show erosions with new bone formation, pencil-in-cup deformity, periostitis and asymmetric sacroiliitis or bulky syndesmophytes. Ultrasound and MRI detect early synovitis, enthesitis and sacroiliitis.

Differential diagnosis

  • Rheumatoid arthritis
  • Erosive hand osteoarthritis (Heberden nodes)
  • Gout
  • Reactive arthritis
  • Ankylosing spondylitis
  • Enteropathic arthritis

Goal of treatment

Reach remission or low disease activity across all domains (joints, spine, entheses, dactylitis, skin and nails), prevent joint damage and manage cardiovascular and metabolic comorbidity.

Treatment

Medical
Non-steroidal anti-inflammatory drugs and intra-articular glucocorticoids for symptom relief; systemic glucocorticoids are used sparingly because stopping them can flare psoriasis.
Medical
Conventional synthetic DMARDs (methotrexate, leflunomide, sulfasalazine) for peripheral arthritis; they do not help axial disease.
Medical
Biologic DMARDs (TNF, IL-17, IL-12/23 and IL-23 inhibitors), JAK inhibitors and PDE4 inhibitors for active or axial disease, enthesitis or poor response.
Rehabilitation
Physiotherapy, exercise and joint protection.
Lifestyle
Weight loss, stopping smoking and control of cardiovascular risk factors.
Follow-up
Monitoring of disease activity, liver tests and blood counts on methotrexate, and of infections on biologics after tuberculosis screening.

Drugs for this condition

Complications

  • Permanent joint destruction and deformity (arthritis mutilans)
  • Spinal fusion and reduced mobility
  • Uveitis
  • Cardiovascular disease, metabolic syndrome, fatty liver and diabetes
  • Infections on immunosuppressive therapy
  • Depression and reduced quality of life

Prognosis

Course ranges from mild to destructive. Early diagnosis and treat-to-target therapy limit damage; polyarticular onset, high inflammation and early erosions predict a worse outcome. Cardiovascular risk is increased.

Test yourself

Think of the answer, then tap the question to see it.

What is the classic radiographic deformity of psoriatic arthritis?

Pencil-in-cup deformity of the distal interphalangeal joints, with erosions plus new bone formation.

Which clinical features suggest psoriatic rather than rheumatoid arthritis?

DIP involvement, dactylitis, nail pitting, asymmetric pattern, enthesitis, axial disease and negative rheumatoid factor.

Why are systemic glucocorticoids used sparingly in psoriatic disease?

Their withdrawal can trigger a severe psoriasis flare, including pustular psoriasis.

What screening is required before starting a TNF inhibitor?

Screening for latent tuberculosis (and hepatitis B and C).

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: Psoriatic arthritis (MedlinePlus (U.S. National Library of Medicine), 2025).

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Representative model, for educational purposes only.

Finger joint capsules highlighted on the Durgical 3D model