Psoriasis

DEFINITION

Psoriasis is a common skin condition that changes the life cycle of skin cells. Psoriasis causes cells to build up rapidly on the surface of the skin. The extra skin cells form thick, silvery scales and itchy, dry, red patches that are sometimes painful.

Psoriasis is a persistent, long-lasting (chronic) disease. There may be times when your psoriasis symptoms get better alternating with times your psoriasis worsens.

The primary goal of treatment is to stop the skin cells from growing so quickly. While there isn’t a cure, psoriasis treatments may offer significant relief. Lifestyle measures, such as using a nonprescription cortisone cream and exposing your skin to small amounts of natural sunlight, also may improve your psoriasis symptoms.

CAUSES

The cause of psoriasis isn’t fully known, but it’s thought to be related to an immune system problem with cells in your body. More specifically, one key cell is a type of white blood cell called a T lymphocyte or T cell. Normally, T cells travel throughout the body to detect and fight off foreign substances, such as viruses or bacteria. If you have psoriasis, however, the T cells attack healthy skin cells by mistake, as if to heal a wound or to fight an infection.

Overactive T cells trigger other immune responses. The effects include dilation of blood vessels in the skin around the plaques and an increase in other white blood cells that can enter the outer layer of skin. These changes result in an increased production of both healthy skin cells and more T cells and other white blood cells. This causes an ongoing cycle in which new skin cells move to the outermost layer of skin too quickly — in days rather than weeks. Dead skin and white blood cells can’t slough off quickly enough and build up in thick, scaly patches on the skin’s surface. This usually doesn’t stop unless treatment interrupts the cycle.

Just what causes T cells to malfunction in people with psoriasis isn’t entirely clear. Researchers have found genes that are linked to the development of psoriasis, but environmental factors also play a role.

Psoriasis triggers

Psoriasis typically starts or worsens because of a trigger that you may be able to identify and avoid. Factors that may trigger psoriasis include:

• Infections, such as strep throat or skin infections
• Injury to the skin, such as a cut or scrape, bug bite, or a severe sunburn
• Stress
• Cold weather
• Smoking
• Heavy alcohol consumption
• Certain medications — including lithium, which is prescribed for bipolar disorder; high blood pressure medications such as beta blockers; antimalarial drugs; and iodides.

SYMPTOMS

Psoriasis signs and symptoms can vary from person to person but may include one or more of the following:

• Red patches of skin covered with silvery scales
• Small scaling spots (commonly seen in children)
• Dry, cracked skin that may bleed
• Itching, burning or soreness
• Thickened, pitted or ridged nails
• Swollen and stiff joints

Psoriasis patches can range from a few spots of dandruff-like scaling to major eruptions that cover large areas.

Most types of psoriasis go through cycles, flaring for a few weeks or months, then subsiding for a time or even going into complete remission.

Several types of psoriasis exist. These include:

• Plaque psoriasis. The most common form, plaque psoriasis causes dry, raised, red skin lesions (plaques) covered with silvery scales. The plaques itch or may be painful and can occur anywhere on your body, including your genitals and the soft tissue inside your mouth. You may have just a few plaques or many.
• Nail psoriasis. Psoriasis can affect fingernails and toenails, causing pitting, abnormal nail growth and discoloration. Psoriatic nails may become loose and separate from the nail bed (onycholysis). Severe cases may cause the nail to crumble.
• Scalp psoriasis. Psoriasis on the scalp appears as red, itchy areas with silvery-white scales. The red or scaly areas often extend beyond the hairline. You may notice flakes of dead skin in your hair or on your shoulders, especially after scratching your scalp.
• Guttate psoriasis. This primarily affects young adults and children. It’s usually triggered by a bacterial infection such as strep throat. It’s marked by small, water-drop-shaped sores on your trunk, arms, legs and scalp. The sores are covered by a fine scale and aren’t as thick as typical plaques are. You may have a single outbreak that goes away on its own, or you may have repeated episodes.
• Inverse psoriasis. Mainly affecting the skin in the armpits, in the groin, under the breasts and around the genitals, inverse psoriasis causes smooth patches of red, inflamed skin. It’s worsened by friction and sweating. Fungal infections may trigger this type of psoriasis.
• Pustular psoriasis. This uncommon form of psoriasis can occur in widespread patches (generalized pustular psoriasis) or in smaller areas on your hands, feet or fingertips. It generally develops quickly, with pus-filled blisters appearing just hours after your skin becomes red and tender. The blisters may come and go frequently. Generalized pustular psoriasis can also cause fever, chills, severe itching and diarrhea.
• Erythrodermic psoriasis. The least common type of psoriasis, erythrodermic psoriasis can cover your entire body with a red, peeling rash that can itch or burn intensely.
• Psoriatic arthritis. In addition to inflamed, scaly skin, psoriatic arthritis causes pitted, discolored nails and the swollen, painful joints that are typical of arthritis. Symptoms range from mild to severe, and psoriatic arthritis can affect any joint. Although the disease usually isn’t as crippling as other forms of arthritis, it can cause stiffness and progressive joint damage that in the most serious cases may lead to permanent deformity.

When to see a doctor

If you suspect that you may have psoriasis, see your doctor for an examination. Also, talk to your doctor if your psoriasis:

• Progresses beyond the nuisance stage, causing you discomfort and pain
• Makes performing routine tasks difficult
• Causes you concern about the appearance of your skin
• Leads to joint problems, such as pain, swelling or inability to perform daily tasks

Seek medical advice if your signs and symptoms worsen or don’t improve with treatment. You may need a different medication or a combination of treatments to manage the psoriasis.