• Psoriatic arthritis (PsA) is seronegative spondyloarthropathy usually seen in patients with psoriasis
• The severity and duration of psoriasis increase the risk of developing PsA.
• In the majority of patients, psoriasis begins before arthritis. In a small proportion, arthritis begins earlier or together with psoriasis.
clinical findings
joint findings
• 5 different joint involvement patterns have been defined in PsA:
o Asymmetric oligoarthritis: It is the most common involvement pattern of the disease (Cecil 2020).
o Symmetrical polyarthritis: May resemble rheumatoid arthritis. In fact, autoantibodies (RF, ANA, anti CCP) may be positive in some of the patients.
o DIF joint arthritis: Only DIFs are involved. Often there are psoriatic changes (onycholysis, pitting) in the nails.
o Psoriatic spondylitis: Spinal involvement and sacroiliitis are prominent. It is the pattern with the highest HLA-B27 positivity rate.
o Arthritis mutilans (rare}: It is the most severe pattern with erosion and destruction of the joints.Telescopic finger (shortening of the finger) may develop.
• Dactylitis (sausage finger)
o It is an enthesitis/tenosynovitis that describes swelling and redness of the entire finger.
o Among all SpA types, it is most common in ReA and PsA.
Radiological findings
• Pencil in cup deformity caused by DIF involvement
• Bone proliferation adjacent to the joint
• Absence of periatricular osteoporosis
• Osteolysis in the phalangeal and metacarpal bones (telescopic finger)
• Sacroileitis (asymmetrical), spondylitis, syndesmophyte.
Diagnosis
CASPAR criteria
Evidence of the presence of psoriasis
psoriatic nail dystrophy
RF negative
typewriter
Radiological findings (bone proliferation adjacent to the joint)
3 criteria are sufficient in a patient with inflammatory joint disease.
Treatment
• DMARDs such as leflunomide, sulfasalazine, etc., especially methotrexate, are generally effective on both skin and joint findings.
• Biological therapy is started in resistant or severe cases:
o Anti TNF drugs: Infliximab, etanercept, adalimumab, golimumab, certolizumab
o IL-12/IL-23 inhibitor: Ustekinumab
o IL-17 inhibitors: Secukinumab, Brodalumab, Ixekizumab
o Phosphodiesterase 4 inhibitor: Apremilast
o JAK inhibitor: Tofacitinib