Psoriasis is an inflammatory disease of the skin, the nails, and sometimes the joints. As it affects approximately 2% of the population, it is one of the most common diseases seen by dermatologists. Psoriasis most often appears between the ages of 20 and 30, but can begin at any age. For most people, psoriasis is a lifelong disease that can be controlled with proper treatment but not cured.
Skin lesions usually look like round, red, scaly plaques. They most commonly appear on the elbows, knees, scalp, and lower back, but may occur anywhere on the skin. Most often only a few small places on the body are involved, but occasionally most of the skin surface is involved. In some people the lesions come and go, whereas in other people the lesions are stable or even spread over time. Trauma to the skin can cause new lesions to form. Psoriasis of the skin can have a negative impact on one’s quality of life not only because of the appearance of the skin lesions, but also because the lesions are sometimes itchy.
The nails are involved in up to 80% of people with psoriasis. Since the nails are often thickened and yellowish, this condition is sometimes confused with fungus of the nails. Also, small pits or indentations can occur on the nail surface and darker yellow-brown spots can occur under the nail. Psoriasis of the nails can be painful.
In 5-30% of people with psoriasis, the joints are also affected. Most commonly, the finger and toe joints are involved. Skin lesions usually appear before joint involvement.
While psoriasis does tend to run in families, other factors are involved as well. Recently, studies have shown that the occurrence psoriasis is increased in smokers and in those who are overweight. There is also a correlation with coronary artery disease. Occasionally, infections (such as Strep throat) can precipitate psoriasis in susceptible people.
Stress and certain medications (such as lithium, beta blockers, and interferon) can also induce or aggravate psoriasis.
There are many effective treatments to control psoriasis. Medications can clear the skin lesions and improve joint problems, but cannot cure the disease. Therefore, most people require lifelong treatment. Nail psoriasis is much more difficult to treat.
For areas of skin involvement, multiple types of creams, ointments, foams, and lotions are available. Most of these topical medications are anti-inflammatory corticosteroids. Topical vitamin D and vitamin A derivatives are sometimes used. Alternatively, ultraviolet light treatments can be used for skin involvement.
For people with more extensive disease or significant joint involvement, oral medications and injectable medications are available. Most of these therapies suppress the immune system (decrease your ability to fight off infections), so a careful review of side effects is needed. Your dermatologist can discuss the different treatment options with you.