Psoriatic Arthritis

Question 1

What are the characteristics of seronegative arthirides

Answer 1

Seronegative = negative for rheumatoid factor

Greater male prevalence
Asymmetrical, large lower extremities
Enthesitis, tendinitis, costochondritis
Sacroiliac, axial disease
-AS, non radiographic SpA

Can have multiple seronegative SpA

HLA B27

Question 2

What conditions are seronegative spondyloarthropathy

Answer 2

AS
Reactive arthritis - no infection within joint but inflamed due to cross reactivity of infection elsewhere
IDB
PA
Acute anterior uveitis - uvea (iris, ciliary body, choroid)
Juvenile idiopathic arthritis
Undifferentiated spondyloarthropathy - large swollen joints

Question 3

What are the joint changes that accompany PA

Answer 3

DIP, PIP synovitis (DIP changes only in OA, PA)
Asymmetric oligoarthritis (up to 4)
Dactylitis, enthesitis (characteristic of PA
Psoriatic nail changes

Highly immune cell infiltrated synovial membrane (like RA)

May be

• polyarticular (many small joints)
• oligoarticular (few large joints)
• spondyloarthritis (sacroiliac joint, spine)
• arthritis mutilans

Question 4

Describe the radiological features that you may find with SpA

Answer 4

Loss of joint space due to joint erosion => new bone forms, ankylosed

May turn into arthritis mutilans

Question 5

Describe the epidemiology of PA

Answer 5

Equigender
Not all psoriasis patients have PA
-severity of psoriasis correlated with occurrence of PA
-psoriasis generally precedes PA

Question 6

What cytokines are key in the pathophysiology of

• Psoriasis
• RA, Gout crystal arthropathy
• Gout

Answer 6

All impacted by TNFa
Psoriasis => IL 17-23
RA, GCA => IL6
Gout => IL1

Question 7

Describe the pathophysiology behind the immune component of PA

Answer 7

Il23 => Differentiation into Th17

Th17, mast, neutrophils release IL17

• cutaneous lesions
• inflammation
• cartilage damage
• bone erosion

Question 8

How would you treat SpA

How would you treat RA

Answer 8

TNF inh = good for both (inflixumab, adalimumab)

IL6 inh = RA (tocilizimab)
B cell depletion via CD20 = RA (rituximab)
T cell activation inh = RA (abatacept)

IL17,23 inhibitors = SpA (secukinumab, ustekinumab)