Psoriatic Arthritis

Question 1

What is Psoriatic Arthritis?

Answer 1

An arthritic condition affecting those with psoriasis, however the arthritis can precede the skin lesions

It is part of a group of inflammatory conditions (Seronegative arthropathies), which share similar clinical features, pathological findings, the absence of rheumatoid factor and a strong association with the histocompatibility antigen HLA-B27.

They comprise:
Ankylosing spondylitis
Psoriatic arthropathy
Reactive arthritis - Aseptic inflammation of joints following infection

These conditions share many common clinical features

Question 2

What will you find on history of Psoriatic Arthritis?

Answer 2

Symptoms:
Asymmetrical large joint oligoarthritis or monoarthiritis with swelling, pain and stiffness
Spinal arthritis/sacroiliitis
Inflammatory type pain - morning stiffness >30 minutes, improvement with use, worse at night
Dactylitis (‘sausage digits’) are common and diagnostic
Psoriasis

Seronegative Symptoms - make this common to all of the seronegative spondlyarthroapthies
Sacroiliitis
Achilles tendinitis
Plantar fasciitis
Uveitis/Conjunctivitis - Red painful eyes

Risk Factors:
More common in women

Specific Questions to ask:
How are they dealing/being affected
Diabetes or high cholesterol? As there is a link to metabolic disease
Personal or family history of psoriasis or history of scalp or nail problems
Ask about exacerbating factors - Smoking, Alcohol, stress

Differentials:
Rheumatoid Arthritis - Symmetrical, no spinal involvement and no Dactylitis
Reactive Arthritis - Recent exposure to certain gastrointestinal and genitourinary infections
Ankylosing Spondyltiits - Shobers tests
Gout - Acute presentation with quick resolution. Swelling effusion, warmth of joint, commonly affects big tow

Question 3

What will you find on examination of Psoriatic Arthritis?

Answer 3

Hands:
Psoriasis on extensor limbs/elbows 
Nails pitting or onycholysis.
Dactylitis - Diagnostic 
Blood pressure - Metabolic Syndrome associated 

Face:
Psoriasis on scalp

Chest:
Exclude Ankylosing Spondylitis with schobers test

Abdomen:
Periumbillical Psoriasis

Legs:
Psoriasis between butt cheeks or perineum
Tenderness over the heel (either plantar fascia or Achilles tendon)

Question 4

What investigations will you order in Psoriatic Arthritis?

Answer 4

Bloods:
ESR/CRP Raised
Rheumatoid Factor - Will be negative. Done to rule out rheumatoid arthritis
HLA-B27 - Raised in most cases
Lipids/Glucose - Linked to metabolic disease
Uric Acid levels - exclude gout
CPPD crystals - Ruling out pseudogout

Imaging:
Spinal XRay - To look for sacroiliitis
Xray of Hand and feet - Erosion in the distal interphalangeal (Pencil Cup Deformtiy) joint and periarticular new-bone formation
Foot X-ray -Calcaneal spur if any plantar fasciitis

Question 5

What is the treatment of Psoriatic Arthritis?

Answer 5

Refer to rheumatologist

Medical:
1st line - NSAIDS
2nd Line - Methotrexate/Sulasalazine
3rd Line - Anti TNF Alpha
Oral or Topical corticosteroids for psoriasis on skin
Local steroid injections are useful for joint and soft tissue inflammation.