Association between flares of skin and nail disease and flares of Psoriatic arthritis
The relationship between skin and joint disease activity is variable.
Patients with simultaneous onset of psoriasis and PsA have reported that when one manifestation flares, the other is likely to flare.
However, for most patients the skin and arthritis run separate courses. Patients with DIP involvement are more likely to have worse nail involvement.
This is partly because the extensor tendon enthesis inserts in an area adjacent to the nail root.
When the enthesis becomes inflamed, nail growth is affected adversely.