Psoriatic arthritis occurs in patients who have skin or nail psoriasis. Imbalances in the cytokine (chemical messengers produced by cells to control activities of other cells) result in skin cell turning around more than normal. These imbalances also result in joint swelling and pain. Severe forms may cause the bone to be eroded. The patient typically presents with pain and swelling of 2 or 3 joints, sometimes severe. Persists day and night. In the majority of patients skin rash suggestive of psoriasis precedes the joint pain. Swelling lasts for a very long time despite treatment. In some patients especially the ones having palmo plantar psoriasis (hands and feet), the joint pain is intense and objective signs such as swelling are minimal and hence making a diagnosis is a challenge. Occasionally the joint pain may occur before the skin lesion. But usually a family history of psoriasis is present.
There are no tests to identify psoriatic arthritis. CRP a marker of inflammation is usually elevated. X rays and MRI may show joint inflammation and damage.The usual pattern of arthritis (1-3 joints, asymmetric, whole toe or finger swelling) with the typical skin rash of psoriasis is adequate to make the diagnosis of psoriatic arthritis. Uric acid levels may be high and gout flares may also be seen. Please see gout section for more details.
NSAIDs, antiinflammatory drugs provide pain relief. Mild disease needs no further treatment. Fish oil capsules and vitamin D such as alphacalcidiol may be helpful. Persistent joint inflammation requires medications like methotrexate, leflunamide and occasionally steroids for a short duration. Biologics like etarnecept and infliximab are helpful. Newer biologics for psoriatic arthritis such as apremilast and usteki are currently unavailable in India.