UW MSK Resident Projects
University of Washington, UWMC Roosevelt Clinic, Musculoskeletal Radiology

Home

About


Psoriatic Arthritis

Print-friendly version of this page

Posted by klinnau@u.washington.edu, 10/16/03 at 9:16:58 AM.

Psoriatic arthritis (PsA)

  • 2-17% of patients with psoriasis get arthritis
  • skin lesions and arthritis are often asynchronous: 80-85% of pts have skin lesions first
  • synovial inflammation leading to bony proliferation at joint margins
  • inflammation at the ligamentous attachments: enthesopathy

Age of onset usually 30-45 years, no gender preference

Prognostic factors:

poor prognosis:

  • late age of onset
  • five or more effused joints
  • high immunosuppressive medication use

good prognosis:

  • ESR < 15 mm/h

other labs:

  • HLA B27 positive in 60-80% of psoriatic spondylitis and 20% of peripheral PsA
  • CRP - usually elevated
  • may be elevated: acute serum amyloid A (A-SAA)
  • ANA may be mildly elevated
  • Rheumatoid factor negative (or mildly elevated with titer<1/40, which is cut-off for Rheumatoid Arthritis (RA))

Hypothesis:

Joint damage occurs maximally during first 2 years of disease:

early diagnosis

aggressive treatment

Patterns of presentation:

  1. asymmetric oligoarthritis: > 50%
  2. polyarthiritis with predominantly DIP involvement (classic): 5-19%
  3. symmetric seronegative polyarthritis simulating RA: up to 25%
  4. sacroiliitis and spondylitis resembling Ankylosing Spondylitis (AS): 20-40%
  5. arthiritis mutilans with resorption of the phalanges: 5%

 

Onset may be

insidious (66%) or

acute (33%) mimicking gout or septic arthritis

 

Radiology findings:

Early findings:

  • normal
  • soft tissue swelling: sausage fingers or fusiform swelling about finger joint
  • usually no osteoporosis (˙≠ RA)
  • prominent erosions in marginal areas of joints
  • Perisostitis in metaphysis and diaphysis
  • asymmetric paravertebral ossification of thoraco- lumbar junction (from vertebral body to body  ˙≠  AS: corner to corner)
  • bone scans may show hot spots prior to radiographic abnormality

Distribution of radiographic findings:

  • synovial or cartilaginous joints and tendon attachment of axial and appendicular skeleton (= Reiter = AS ˙≠ RA)
  • unilateral or asymmetric (˙≠ RA) at the hands and feet
  • upper and lower extremity joints (˙≠ Reiter: more commonly lower extremity only)
  • DIP, PIP of hand and foot commonly affected
  • Abnormal phalangeal tufts and calcaneus (characteristic)
  • If axial skeleton: most commonly sacroiliac (SI) and spinal joints

General findings:

  • Soft tissue swelling
  • No osteopenia (˙≠ RA)
  • Joint space may be widened or narrowed
  • Severe marginal erosions gnawing away bone towards the center of the joint are typical
  • Pencil-and-cup appearance of small joints of hand and feet (DDX: RA, leprosy, sarcoid)
  • Bone proliferation (=other seronegative spondylarthropathies = gout): spiculated, frayed, paintbrush appearance (˙≠ RA: no bone deposition)
  • Perisostitis in metaphysis and diaphysis (= Reiter= Juvenile RA =infection) sometimes accompanied by condensation of bone
  • Intraarticular osseous fusion ( AKA bone anklylosis) (DDX: erosive OA, RA (carpus and tarsus), infection, other seronegative spondylarthropathies)
  • Enthesopathy of calcaneus (Achilles tendon), femoral trochanters, ischial tuberosities, malleoli, olecranon, patella, femoral condyles.
  • Tuft resorption of the distal phalanges of the hands and feet (characteristic) (DDX: scleroderma, thermal injury)

Erosions:

  • Start at joint margins, tend to be severe
  • Proceed centrally into joint
  • Result in irregular osseous surfaces: lack of apposition of adjacent bone margins (˙≠ OA)
  • Wrist abnormalities not so common in psoriasis

Calcaneus:

  • Erosion and proliferation of posterior or inferior surface
  • Radiodense area postero-inferior due to retrocalcaneal bursitis
  • Achilles tendon may be thickened.

SI joints:

  • 30-50% of patients with PsA
  • erosions and sclerosis of SI joints
  • bilateral lesions are more common than unilateral

Spine:

  • asymmetric paravertebral ossification of lower thoraco- lumbar junction (from vertebral body to body  ˙≠ AS: corner to corner)
  • Syndesmophytes are greater in size, asymmetric distribution, away form vertebral column  ˙≠ AS
  • squaring of vertebral bodies, apophyseal sclerosis uncommon  ˙≠ AS
  • Cspine abnormalities may be extensive: facets, discovertebral, proliferations along anterior surface, atlantoaxial subluxation, dens erosions.

Scintigraphy:

  •  bone scans may show abnormality prior to radiographs
  • asymmetric  ˙≠ RA
  • DIP, PIP >> SI, calcaneus

 



PsoriaticLSpinesmall:
Lumbar spine showing bilateral sacroiliitis

PsoriaticHeelsmall:
Psoriatic arthritis with proliferative osteophyte on heel

PsoriaticHeelMRT1:
T1-weighted sagittal MR of psoriatic involvement of retrocalcaneal bursa and distal Achilles tendon

PsoriaticHeelMRT2:
T1-weighted sagittal MR of psoriatic involvement of retrocalcaneal bursa and distal Achilles tendon

PsoriaticBoneScanSmall:
Radionuclide bone scan in a patient with psoriatic arthritis and a swollen 5th finger. This delayed image shows markedly increased uptake in the 5th finger.

PsoriaticHandSmall:
Hand film from same patient shows swollen 5th digit from psoriatic arthritis.

PsoriaticFingerSmall:
Detail view of 5th finger from same patient shows erosions from psoriatic arthritis.

Discuss

This page was last updated: Thursday, August 4, 2005 at 11:45:44 AM
Copyright 2005 UW MSK Resident Projects
Create your own Manila site in minutes. Everyone's doing it!

This site is using the Default theme.