Q. My brother developed itchy and scaly patches on the skin of his elbows. He consulted a dermatologist who told him he has psoriasis. He was prescribed an ointment, and luckily his skin cleared up after a few days.  What causes psoriasis? Is it contagious?

–ElmaP@yahoo.com

A. Psoriasis is not an infection and is thus not contagious. It is caused by a malfunction of the body’s immune system that results in the proliferation and abnormal maturation of the cells on the outer layer of the skin that is accompanied by inflammation and abnormalities of the blood vessels.

Psoriasis is a common disease that affects two to four percent of the population. It affects both sexes and all age groups, but usually adults. It runs in families and researchers have already identified genes that are linked to the disease.

The skin lesions that characterize psoriasis consist of red and well-demarcated patches that are often covered by silvery scales. They can occur anywhere, but usually the areas involved are the elbows (as in the case of your brother), knees, lower back, and buttocks. It is, however, not unusual for lesions to develop on the scalp, genitalia, and even the face. Occasionally, the nails are also affected—they thicken and deform. As a rule, psoriasis affects only the skin although occasionally, it complicates and produces swelling and pain in some joints (psoriatic arthritis).

In psoriasis, the area of skin involved can vary from a few small spots to nearly complete body coverage. When only small areas are involved, there is usually no accompanying sign or symptom, except for occasional itchiness and soreness. Extensive body coverage however, is invariably accompanied by itchiness, tenderness and/or bleeding. In any case, the physical discomforts associated with psoriasis are generally tolerable, but the skin rashes are unsightly and often cause embarrassment and psychological distress.

Once it has appeared, psoriasis persists for life, although in most people, appearance of the skin lesions (called a flare-up) is followed by a prolonged period of remission that lasts for months to years. Psoriasis flare-ups can be precipitated by intake of drugs like lithium and beta-blockers (used in hypertension), stress, alcohol, injury, or physical irritation of the skin and upper respiratory tract infection, but some occur without any precipitating cause. Sunburn also exacerbates psoriasis, although moderate exposure to the sun is beneficial.

There is no cure for psoriasis yet. However, there are a variety of treatment regimens currently available to alleviate the active skin lesions, but none is consistently effective in inducing long-term remissions. Furthermore, a treatment regimen that works very well in one person may have little effect in another. Often, a regimen that works is found only after a series of trial and error attempts. 

In general, initial treatment of psoriasis involves application of a topical medicine, which could be a steroid preparation, retinoid (synthetic vitamin A), dithranol, calcipotriol (a vitamin D analog), anthralin, or coal tar.

For psoriasis that involves more than 30 percent of the body surface and those unresponsive to topical treatment, exposure of the affected areas to ultraviolet (UV) light several times a week for many weeks is utilized.  Alternately, Psoralen and ultraviolet A phototherapy (PUVA) can be employed. This treatment combines oral or topical administration of psoralen with exposure to ultraviolet A (UVA) light. PUVA treatment clears psoriasis more consistently and in fewer treatments, but it is associated with more side effects.

In flare-ups that are refractory to topical and UV therapy, use of systemic drugs that are taken internally to suppress the immune system such as cyclosporine and methotrexate are resorted to.

Most of the treatment modalities for psoriasis especially the systemic drugs and UV light have serious adverse effects. UV light can cause nausea, headache, fatigue, burning and itching. It also increases one’s risk of developing skin cancer. The systemic drugs on the other hand are highly toxic. Hence, treatment of intractable psoriasis should be under the supervision of a physician.

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