Psoriasis is a common disorder marked by raised, inflamed lesions that join together to form patches with distinct borders on the skin. The lesions are covered with flaky scales due to the rapid turnover of cells in the epidermis. Psoriasis is not contagious and may be minor or serious. According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, about 2 percent of all people in the United States have psoriasis. Most develop the disease before the age of 40.
It is not known what causes the short cycling of skin cells that leads to psoriasis, but a faulty immune system seems to be involved. The development of the disease and flares following remissions usually result from a trigger (e.g., injury, stress, infection, medications).
Psoriasis is recognized by its characteristic lesions. These are raised, swollen, thick patches of red skin covered with flaky scales of dead skin cells that may itch intensely. They vary in size and shape and always have a distinct border. Lesions may occur anywhere, but usually affect the scalp, knees, elbows, naval area, lower back, buttocks or genitalia. Arthritis (joint inflammation) may also be associated.
Psoriasis is usually diagnosed by a physician during a physical examination. If diagnosis is not definite, it can be confirmed with a skin biopsy. Though there is no cure for psoriasis, treatment can help. The goal of treatment is to clear lesions from the skin by reducing the inflammation and slowing down the rapid cell growth and shedding. Treatment may involve phototherapy and/or topical or oral medications, depending on the severity of the psoriasis. Flares can be prevented by identifying and avoiding triggers.
About psoriasis
Psoriasis is a common, chronic skin disorder that can affect any part of the body. It is characterized by raised, inflamed lesions that join together to form plaques (patches) with distinct borders that are covered with flaky scales. It is not contagious, but is related to hereditary factors. Psoriasis is highly variable and often quite different from person to person. It may be no more than a minor cosmetic problem or quite severe, but most cases are mild to moderate. There may be many remissions and flares, but prolonged remissions are rare. In addition, the patient’s quality of life may be affected.
Most cases of psoriasis are not life-threatening, but severe cases may lead to secondary infections, some of which may become serious. Severe psoriasis may also lead to fluid loss and poor circulation (blood flow). In addition, patients undergoing treatments for severe psoriasis may experience adverse side effects from the drugs used.
The skin changes that characterize psoriasis are due to the rapid turnover of cells in the epidermis. Normal skin cells mature in about one month. In psoriasis, new cells are produced, grow to maturity and die quickly, severely reducing the cell cycle to about four days. Because this is believed to be caused by a faulty immune system, psoriasis is considered an autoimmune disease.
According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, about 2 percent of all people in the United States have psoriasis. Although the onset of the disease can occur any time in life, there are two peaks: from 20 to 30 years and from 50 to 60 years of age. In most cases, onset occurs before the age of 40. Men and women are equally affected by the disease, but onset is typically earlier in women. It also occurs earlier in patients with a family history of psoriasis. Psoriasis is more common in Caucasians than in other races.
Types and differences of psoriasis
There are many different types of psoriasis, often with significant overlap. They include:
Plaque psoriasis. The most common form of psoriasis, also called psoriasis vulgaris. Marked by raised, inflamed, red lesions covered with a silvery-white buildup of dead skin cells. The nails may also be affected. According to the American Academy of Dermatology (AAD), about 80 percent of patients with psoriasis have plaque psoriasis.
Psoriatic arthritis. Also called psoriasis arthropica or psoriatic arthropathy. This is psoriasis associated with arthritis, generally similar to rheumatoid arthritis (chronic joint inflammation). While typically milder than rheumatoid arthritis, psoriatic arthritis may be disabling. It frequently involves the fingers and toes. According to the AAD, up to 30 percent of patients with psoriasis have associated arthritis.
Guttate psoriasis. Small, distinct, generally widespread red lesions. Onset is most common in children, particularly after respiratory infections (e.g., strep throat).
Inverse psoriasis. Also known as skin fold psoriasis, flexural psoriasis or genital psoriasis. Smooth, dry, red lesions form in the folds of skin, commonly in the arm pits, genital area and under the breasts. This type occurs most often in patients who are overweight.
Pustular psoriasis. Small, sterile pustules appear, dry up and form a scab. The blisters associated with this form of psoriasis are white and surrounded by red skin. They are typically localized to palms and soles. Pustular psoriasis can be very severe and may be associated with systemic symptoms (e.g., unwell feeling, fever, diarrhea). According to the AAD, pustular psoriasis affects less than 5 percent of patients with psoriasis. This type of psoriasis is particularly worsened by overindulgence of alcohol and overuse of oral steroids.
Erythrodermic psoriasis. Also known as psoriasis universalis. This particularly severe form of psoriasis is characterized by intense redness that covers all or most of the body surface. It often causes dangerously high temperatures and a greatly increased susceptibility to infection, generally requiring hospitalization. This is the least common type of psoriasis.
When injury to the skin leads to the development of psoriasis, it is referred to as Koebner phenomenon. This may result in any type of psoriasis.
Risk factors and causes of psoriasis
The skin changes that characterize psoriasis are due to the rapid turnover of cells in the epidermis. New cells are produced, grow to maturity and die too quickly, severely reducing the cell cycle. Although the cause of this is not known, it is believed to involve a faulty response of the immune system.
There is a genetic factor involved in the development of psoriasis. The disease is seen more commonly in families and, according to the National Institutes of Health, there is a family history of psoriasis in about one-third of all psoriasis patients.
The onset of psoriasis is believed to require a trigger. Triggers may also lead to flares and exacerbations. Common triggers include:
Skin injury, including cuts, bites, bruises, burns, chafing or sunburns
Emotional stress
Viral or bacterial infection (e.g., thrush, HIV, strep throat)
Certain drugs, including antimalarial drugs, beta blockers (used to treat high blood pressure), lithium, and the prolonged use of steroids
Climate, including lack of sunlight and dry weather conditions
Obesity
Hormonal factors, including hypocalcemia (not enough calcium in the blood) and those involved in pregnancy
Alcohol and smoking
Psoriasis triggers will vary from patient to patient. What triggers psoriasis in one person may not cause symptoms in another.
Signs and symptoms of psoriasis
The main symptom of psoriasis is the characteristic lesions. Individual patients may have very different types of lesions. Lesions generally appear as very small, dot-like, red spots at first, then gradually enlarge. The affected skin thickens and often becomes dry, cracked and encrusted. These raised patches are typically swollen (edema), red (erythema) and are often itchy. Lesions are typically covered with flaky, silvery, yellow-white scales. Lesions on the legs may have a blue or purple tint. In children, psoriasis lesions are generally not as thick and may be less scaly. Children also develop facial lesions more often than adults.
The scales on the surface come off easily and are constantly shed. Those below the surface are more difficult to remove and, when removed, often leave tiny bleeding points (Auspitz’s sign). The skin beneath is generally very red and may be tender and painful. In dark-skinned individuals, the lesions beneath the scale layer may be the same color as the rest of the skin instead of a bright red color.
Lesions vary in size and shape, but the borders are distinct. There is usually only one or a few patches, but they may cover large areas of skin and merge into each other. The outlines are usually circular or oval. Sometimes, the lesions are surrounded by a ring of pale skin (Woronoff’s ring). When psoriasis is actively expanding, the itching may be more severe.
Lesions may occur anywhere on the body and can appear suddenly or gradually. In many cases, lesions appear on both sides of the body symmetrically. They frequently occur at sites of skin injury and on the scalp, knees, elbows, naval area, lower back, buttocks and genitalia. They may also occur on the palms, soles, fingernails, toenails or even inside the mouth. The lesions may affect body movement and flexibility and can be disabling when they appear in certain areas (e.g., palms, soles). The itchiness associated with severe cases can also disrupt a person's ability to sleep at night.
Other signs and symptoms may include:
The nails often become pitted. A yellow-brown staining of the nail, lifting of the nail from the nail bed (onycholysis) and ridging and thickening of the nail (nail dystrophy) may also occur.
Unaffected skin may become thin and easily torn.
The eyes may burn, itch or have discharge. Inflammation of the eyelids (blepharitis) or inner eye lining (conjunctivitis) may occur.
When arthritis is associated with psoriasis, joint involvement occurs after skin lesions are already apparent.
It is important to note that with very mild cases of psoriasis, a person may be completely unaware of the condition. However, most cases of psoriasis are moderate and trigger symptoms.
Diagnosis methods for psoriasis
Psoriasis is diagnosed through observation of the lesions during a physical examination. There are no associated blood tests, although x-rays (images of a body part on film paper or fluorescent screens) may be used to look for early signs of arthritis (joint inflammation). If a diagnosis is not definite, it can be confirmed with a skin biopsy.
Psoriasis can be hard to diagnose because many other conditions may be confused for psoriasis. These may include:
Seborrheic dermatitis. A scaly form of dermatitis. This is the most common condition confused with psoriasis.
Eczema. Skin condition with itchy and inflamed lesions, including allergic contact dermatitis and atopic dermatitis.
Sézary syndrome. An itchy, shedding dermatitis.
Pityriasis rubra pilaris. A scaly eruption of the hair follicles.
Pityriasis rosea. Dry, scaly eruptions that disappear spontaneously and typically do not recur.
Parapsoriasis. A generally painless, scaly dermatitis.
Secondary syphilis. Syphilis marked by skin rash.
Impetigo. Bacterial skin infection marked by crusty lesions.
Superficial candidiasis. Yeast infection of the skin.
Treatment of psoriasis
Though there is no cure for psoriasis, treatment may temporarily clear lesions or significantly improve the appearance of the skin. The goal of treatment is to clear lesions from the skin by reducing inflammation and slowing down the rapid cell growth and shedding. Treatment is highly individualized. What works for one patient may not work for another. It may also require periodic adjustment. Once treatment has eliminated present lesions, it is typically discontinued until new lesions appear. Most patients will require lifelong therapy to control the signs and symptoms associated with psoriasis. Patients with severe psoriasis may wish to consult a dermatologist.
Treatment generally focuses on certain factors, including:
Softening and removing scales
Relieving pruritus (itch)
Reducing pain and discomfort
Slowing rapid cell proliferation
Helping to induce remission
Factors that determine the course of treatment to be used include:
Type and severity of psoriasis present
Location and size of lesions on the body
Patient’s overall health, age and medical history
Patient’s tolerance of specific medication, procedures or therapies
Patient and physician’s opinion or preference.
Topical medications may be used to treat mild to moderate psoriasis. They may be used alone, in combination, or with exposure to ultraviolet light. Generally, any existing scales need to be removed before application because they block penetration. This may be accomplished through hydration, such as soaking in a warm bath, or with medications that soften the skin, such as keratolytic agents (e.g., salicylic acid). Topical psoriasis medications include:
Emollients (moisturizers). Mild, non-perfumed moisturizers may be purchased without a prescription. They restore moisture and flexibility to affected skin and may reduce itching, scaling and inflammation. Increased use may be necessary in dry climates or during winter.
Coal tar preparations. These may be applied directly to the lesion, added in bath water as a soak, or used in combination with ultraviolet B (UVB) light. They may be available with or without a prescription. For scalp psoriasis, a coal tar shampoo may be used.
Corticosteroids. These are the most commonly prescribed medications for psoriasis. Though they can be quite helpful in mild to moderate psoriasis, they are not usually effective in severe psoriasis. Prolonged use can even result in rebound psoriasis worse than the original condition.
Anthralin. Reduces increase in skin cells and inflammation. May be used for thicker, harder-to-treat lesions.
Occlusion may be used with topical medications. Lesions are covered with tape dressing, plastic wrap or a special suit. This increases the absorption of the medications.
Phototherapy is often used in the treatment of moderate to severe psoriasis. Natural sunlight or ultraviolet light exposure may help reduce lesions, although care must be taken not to burn. Sunburn can make psoriasis worse. Methods of delivering ultraviolet light include:
Psoralen and long-wave ultraviolet radiation (PUVA). Psoralen is a medication usually applied topically before exposure to ultraviolet A light. PUVA therapy is not recommended in children under the age of 12, pregnant or breastfeeding women or individuals with certain medical conditions (e.g., kidney or liver dysfunction). Possible side effects include sunburn, nausea, vomiting, abnormal hair growth and hyperpigmentation (too much pigment in the skin).
Narrow-band UVB (NB-UVB). Intense ultraviolet B light may also reduce lesions. Advantages over PUVA include shorter treatment times and no need for medications. NB-UVB can be used in children, pregnant or breastfeeding women and people with kidney or liver dysfunction. However, it is not widely available.
Oral medications may be used for severe, life-threatening cases of psoriasis that do not respond to other forms of treatment. They may be used alone or in combination. These can be more dangerous than topical treatments, so the benefits of their use must be weighed against their possible side effects. Some oral medications can cause life-threatening complications. Methotrexate is an antimetabolite that interrupts the growth of skin cells. Patients on this medication must be monitored for liver, kidney and blood changes. Retinoids, which normalize skin cell production, may be prescribed in some cases.
Biologics are the newest treatments for psoriasis. These are drugs administered intravenously (I.V.) or via intramuscular (IM) injection. They treat psoriasis and psoriatic arthritis by working on parts of the immune system which help trigger psoriasis.
People with psoriasis may find some relief from itching by adding Epsom salts or oatmeal to baths. Moisturizing the skin while it is wet may also be soothing.
Psoriasis can have a substantial effect on a person’s self-esteem and social life. In addition, living with the day-to-day discomfort associated with the condition can be frustrating and may add to a person’s stress level. Therefore, patients may benefit from seeking psychological counseling or joining a support group. Anti-anxiety medications or antidepressants may also be recommended.
New research is delving into many psoriasis issues, including:
Understanding the role of family history in psoriasis
New treatments that quiet the immune system
New laser light treatments
Prevention methods
Patients with psoriasis can help prevent flares by identifying and avoiding triggers that cause or worsen psoriasis. These may be different for every patient and may include skin injury (e.g., cuts, abrasions), infection, emotional stress and others.
Tips to avoid flares include:
Live a healthy lifestyle. Patients should eat a balanced diet, drink plenty of water (at least eight 8-ounce glasses a day) and get an adequate amount of sleep. These steps can help the body ward off infection.
Quit smoking. Patients should quit smoking (or not start).
Drink in moderation. Patients should limit their consumption of alcohol. Those taking methotrexate should not consume alcohol at all, due to the risk for side effects.
Take steps to reduce stress. There are a number of stress management techniques patients can use to reduce their stress level, such as yoga and meditation. Exercise can also be helpful in lowering stress levels.
Moisturize the skin. Moisturizers help to relieve dry skin and prevent cracking. They are especially beneficial when applied after bathing.
Avoid scratching or picking at lesions. Patients should not scratch or pick at their skin. This can lead to secondary infection. It can also cause bleeding and worsen the psoriasis.
Avoid hot water. Patients should bathe in warm water to prevent dry skin.
Limit bathing time. Showers and baths should be limited to 15 minutes or less.
Avoid harsh, drying soaps. Non-deodorant and fragrance-free soaps are best.
Avoid rubbing the skin with a towel following a shower or bath. Gently patting the skin dry with a towel will help avoid irritation.
Avoid harsh fabrics. Cotton is the best choice for clothing, as it is less likely than other types of fabric to irritate the skin.
Use a humidifier. Humidifiers help maintain moisture in the air. They are particularly useful during the winter months.
Questions for your doctor
Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following psoriasis-related questions:
What type of psoriasis do I have?
Do you have experience treating patients with psoriasis?
How may my current conditions and medications affect my psoriasis?
What treatment options are right for me?
Does psoriasis pose a danger to my overall health?
Can I transmit psoriasis to other people?
Will my lesions leave scars?
What steps can I take to prevent infection?
How will I know if my skin becomes infected?
How likely is it that my children will develop psoriasis?
