Psoriatic arthritis (also arthritis psoriatica, arthropathic psoriasis or psoriatic arthropathy) is a type of inflammatory arthritis that, according to the National Psoriasis Foundation, affects around 10-30% of people suffering from the chronic skin condition psoriasis.[3] Psoriatic arthritis is said to be a seronegative spondyloarthropathy and therefore occurs more commonly in patients with tissue type HLA-B27.

Treatment of psoriatic arthritis is similar to that of rheumatoid arthritis. More than 80% of patients with psoriatic arthritis will have psoriatic nail lesions characterised by pitting of the nails, or more extremely, loss of the nail itself (onycholysis).

Psoriatic arthritis can develop at any age, however on average it tends to appear about 10 years after the first signs of psoriasis. For the majority of people this is between the ages of 30 and 50, but it can also affect children. Men and women are equally affected by this condition. In about one in seven cases the arthritis symptoms may occur before any skin involvement.