What is this Condition?
Psoriasis is a chronic, recurrent skin disease in which the skin's outermost layer is abnormally overgrown. Red patches form and are covered by thick, dry, silvery scales. These lesions vary widely in severity and distribution.
Psoriatic skin cells have an abnormally short life cycle - 4 days as opposed to 28 days for normal skin cells. Four days isn't enough time for skin cells to mature. As a result, the outermost skin layer becomes thick and flaky.
Typically, the disease goes through partial remissions and flareups. Flare-ups are often related to specific factors but may be unpredictable. They can usually be controlled with therapy.
Psoriasis affects about 2% of the population in the United States.
The incidence is higher among whites than other races. Although this disorder is most common in young adults, it may strike at any age, including infancy.
What are its Symptoms?
The most common symptom of psoriasis is itching; occasionally, pain from dry, cracked, encrusted lesions may occur. These lesions are red and usually form well-defined patches (also called plaques), which sometimes cover large areas of the body. They're most common on the scalp, chest, elbows, knees, back, and buttocks.
The patches consist of silver scales that either flake off easily or can thicken, covering the lesion. If the scales are removed, fine points of bleeding may occur. Occasionally, small teardrop-shaped lesions appear, either alone or with plaques. Typically, these lesions are thin and red, with few scales. Widespread shedding of scales is common in exfoliative (inflammatory) psoriasis and may also develop in chronic psoriasis
Pustular psoriasis is a rare, severe form of the disorder marked by bright red patches and small, raised areas that contain pus.
In about 30% of cases, psoriasis spreads to the fingernails, producing small indentations and yellow or brown discoloration. In severe cases, buildup of thick, crumbly debris under the nails causes them to separate from the nailbed.
Some people with psoriasis develop arthritic symptoms, usually in one or more joints of the fingers or toes, or sometimes in the joints of the lower back. Some people suffer morning stiffness. People with joint symptoms experience remissions and flare-ups similar to those of rheumatoid arthritis.
Scale Removal
To remove psoriatic scales, the doctor may instruct the person to apply ointments, such as Vaseline, salicylic acid preparations, or preparations containing urea. These medications soften the scales; the person then removes them by scrubbing them carefully with a soft brush while bathing.
Ultraviolet Light Treatment
To retard rapid skin cell production, the doctor may recommend exposure to light (either ultraviolet B or natural sunlight) to the point of minimal skin redness. Ultraviolet B light exposure is the most common treatment for generalized psoriasis.
The person may apply tar preparations or crude coal tar to affected areas about 15 minutes before exposure, or may leave these preparations on overnight and wipe them off the next morning. Exposure time can increase gradually. Outpatient or day treatment with ultraviolet B light avoids long hospitalizations and prolongs remission.
Steroid Therapy
Steroid creams and ointments are useful to control psoriasis. A potent fluorinated steroid works well (except on the face and areas where two skin surfaces come into contact). These creams must be applied twice daily, preferably after bathing to promote absorption; overnight, the person covers the areas with occlusive dressings, such as plastic wrap, plastic gloves or booties, or a vinyl exercise suit (under direct medical or nursing supervision). Small, stubborn plaques may require steroid injections into the lesions.
Calcipotriene
Calcipotriene ointment, a vitamin D3 analogue, is a new topical agent used to treat psoriasis.
Therapy for Severe Psoriasis
For someone with severe chronic psoriasis, the doctor may prescribe the Goeckerman regimen, which combines tar baths and ultraviolet B light treatments. This therapy may induce remission and dear the skin in 3 to 5 weeks. The Ingram technique, a variation of the Goeckerman regimen, uses anthralin instead of tar.
In a therapy called PUVA, the person first receives psoralens (an agent that promotes the action of ultraviolet light) and then is exposed to high-intensity ultraviolet A light.
As a last resort, a drug that inhibits cell proliferation - usually Rheumatrex - may help to relieve severe psoriasis that's unresponsive to conventional treatment.