Inflammatory arthritis associated with psoriasis, but 10-15% of patients can have PsA without psoriasis
Aetiology Occurs in up to 30% of people affected by skin psoriasis Clinical presentation Articular symptoms Usually an asymmetrical oligoarthritis but can affect the hands in a similar pattern to RA Predominantly affects joints of hands and feet 20% of cases involve sacro-iliac joints Some patients have a prediliction for arthritis of the DIP joints of the fingers and/or toes Spondylitis, actylisis and enthesitis commonly occur Extra-articular symptoms Nail involvement (pitting, onycholysis) Clinical subgroups Confined to DIP joints hands/feet Symmetric polyarthritis (similar to RA) Spondylitis (spine involvement) +/- peripheral joint involvement Asymmatric oligoarthritis with dactylitis 5% of patients have a particularly aggressive and destructive form of the condition known as arthritis mutilans - usually occurs in the hands, involves the reabsorption of bone and collapse of soft tissue Investigations Bloods - ↑ inflammatory markers, negative RF X-ray Marginal erosions and 'whiskering' Osteolysis Enthesitis Management Non-pharmacological Physiotherapy, occupational therapy, orthotics, chiropodist Pharmacological Symptomatic - corticosteriods/joint injections, topical steriod eyedrops DMARDs e.g. methotrexate, sulfasalazine, leflunomide Anti-TNF in severe disease unresponsive to NSAIDs and methotrexate Consider other biologics if still unresponsive e.g. secukinumab (anti-IL17)