Sometimes the nails are affected, causing pitting and scaling of the base, or ridging and furrowing with an alteration in the transparency of the nail. Emotional response to the persistence and cosmetically disfiguring effects of psoriasis can be severe. To date, no other disease, with the exception of psoriatic arthritis, has been associated with psoriasis. Psoriasis, however, can appear simultaneously with any other disease. Statistically, about 10 percent of people with psoriasis develop a kind of arthritis known as psoriatic arthritis.
Some physicians feel that psoriatic arthritis is even more common.
Psoriatic arthritis causes pain, swelling and tenderness of the joints and the tissue around the joints. The joint may not move easily. Prompt treatment can relieve pain and inflammation and possibly help prevent joint destruction if severe arthritis is present. Psoriatic arthritis is classified as different from other arthritic diseases. Anyone can develop psoriasis, though heredity seems to play a role.