What Is Psoriasis?
Psoriasis is a red and scaling disease of the skin, which affects 2 to 3% of the UK population.The skin is made up of several layers of cells. In the epidermis (outer layer) the cells change gradually as they move towards the surface where they are continually shed. This process normally takes between 21-28 days. In psoriasis, the rate of turnover is dramatically increased within the affected skin so that the process takes as little as 3 - 7 days. This means that even live cells can reach the surface and accumulate with dead cells. The reasons for this are still not fully understood. Psoriasis is not contagious.
What does Psoriasis look like?
Patches of psoriasis (often known as plaques) are red but covered with silvery white scales, can appear in a variety of shapes and sizes and have well defined edges from the surrounding skin. Some can appear if the skin has been damaged. Patches triggered this way tend to be long and thin. Psoriasis can itch and painful splits may form within it. 5-10% of those who have psoriasis may also have stiff painful joints, which can be due to an associated psoriatic arthropathy. The joints most commonly affected are those at the ends of the fingers and toes. The severity of psoriasis varies from time to time and from person to person. When it is mild there may be only one or two plaques, when it is more severe there may be large numbers of plaques.
Is Psoriasis inherited?
No one fully understands what causes psoriasis yet, but doctors have several theories. We have known for a long time that psoriasis seems to run in families. This is not to say that if you have the disease your children definitely will, or that if your parents didn't you won't either. Rather, there is a marked increase in psoriasis among people whose parents, grandparents or siblings have the disease. If one spouse has psoriasis, a couple's children have a one-in-four chance of developing psoriasis too. If both parents have psoriasis, there is a 50 : 50 chance that their children will inherit the disease. If one fraternal twin has psoriasis, there is a 70% chance that the other will, and there is a 90% chance that if one identical twin has the disease, so will the other.
What types of Psoriasis are there?
The following are the most common varieties:
Common plaque psoriasis - Also known as psoriasis vulgaris, this is the most common type. It appears as raised red scaling patches. The scales, which are often silvery and thickened, appear most frequently on the elbows, knees, scalp and lower back. However, all parts of the skin may occasionally be subject to psoriasis.
Guttate psoriasis - This type of psoriasis often starts in childhood or teenage years, with the sudden onset of small, drop like patches of scaling skin, much thinner than plaque psoriasis. Often covers large parts of the body, but it responds rapidly to ultraviolet therapy and some other forms of treatment. Often a sore throat caused by streptococcal infection will prompt the appearance of guttate psoriasis.
Skin-fold flexural and genital psoriasis - This type of psoriasis occurs in the skin-folds or flexures and can cause great discomfort when one part of the skin rubs against another. This discomfort can be so severe as to become disabling for the patient. It can occur in genital areas, which can lead to discomfort and difficulties with sexual relations. It is more common and troublesome in overweight people.
Erthrodermic or exfoliative psoriasis - This type of psoriasis covers the body completely and can feel extremely uncomfortable. Controlling the body temperature, especially during very hot or very cold climates, can be very difficult. Older people, particularly those with heart disease and heart failure, can also develop problems from accelerated heart rate due to increased blood supply flowing through the severely inflamed skin. This can lead to heart failure.
Localised pustular psoriasis - of palms and soles This is an unusual form of psoriasis and is often found on the palms of the hands or the soles of the feet. Instead of thickened scaling patches, brownish or whitish dots are surrounded by inflamed red skin. Plaques and patches of regular psoriasis can also be present.
Generalised pustular psoriasis - This is a very severe form of psoriasis in which the skin is covered with non-infected pustules, which are collections of white blood cells appearing in the skin. Patients feel very ill and frequently have fever. Psoriasis of this type may be caused by a number of things, including infections, medications such as lithium, or the use of systemic cortisones. It may also occur as a reaction to severe sunburn. It requires urgent dermatological care but fortunately is very rare.
Eczema type psoriasis - This type of psoriasis is most commonly found on the hands or feet. It is frequently itchy and very inflamed with painful cracks or fissures.
How is Psoriasis diagnosed?
When psoriasis is diagnosed by a specialist Dermatologist, a biopsy is not usually necessary. If a sore throat has triggered an attack of psoriasis, your doctor may take a swab from your throat to see if bacteria known as beta-haemolytic streptococci are present. If they are, a course of antibiotics may help. Full history, including family history and skin examination will usually make the diagnosis. If you are suffering from painful joints, your doctor may take a blood test and x rays to decide if you have arthritis with your psoriasis, this happens in about 10% of psoriasis sufferers.
How can Psoriasis be treated?
Treatment will depend on the type and severity of psoriasis. Treatments that are applied directly to the skin are known as topical therapies. These may include:
Topical steroids: corticosteroids and cortisones Steroids can be applied as ointments, creams, lotions, aerosols or tapes. Thick, plaque-type psoriasis on elbows, knees, palms, soles and other thickly skinned areas tends to resist steroids and requires other topical therapy. Alternatively, lesions in body folds, the groin area, eyelids and other thinly skinned areas are usually more sensitive to steroid treatment. Topical steroids can be used to complement other forms of topical therapy, such as tar and ultraviolet light or tazarotene gel, but they are not meant to replace them. When using topical steroids, apply them sparingly to the skin lesion as a thin film. Strong steroids should not be applied to the face or skin folds. If skin irritation, bruising, ulcers or skin infections occur, stop the treatment immediately and consult your doctor. Some patients see a worsening of their psoriasis after using steroids. Overuse or incorrect use can cause the skin to become very thin. This can sometimes be reversed once the medication has been stopped. Thinning skin is a particular problem with babies and young children as their skin is naturally thin. As a result, long term applications of strong topical steroids in young patients are usually avoided. Other side effects of steroids include acne, rosacea, secondary infections of the skin and dermatitis.
Topical vitamin D treatments
Most patients get improvement with vitamin D treatments such as calcipotriene, calcipotriol and unlike topical corticosteroids, do not cause skin thinning or the sudden worsening of psoriasis that sometimes follows the discontinuation of the topical corticosteroid. Some patients develop skin irritancy around the psoriasis areas and the ointment may also produce a skin rash if applied to the face. It is available in cream, ointment and scalp formulations. Curatoderm ointment is another vitamin D treatment that can be used on the face. These treatments are often effective for plaque like psoriasis. Dovonex scalp solution may be useful in mild types of scalp psoriasis but generally is only partly effective for more chronic or severe scalp psoriasis. They are a safe and frequently effective way of improving psoriasis and can be used for a long period of time, however, irritation can occur, especially on the face, bottom and genitals.
Coal tars seem to be the most effective in controlling psoriasis. Used alone they are not very effective but when used in conjunction with ultraviolet therapy, topical corticosteroids and/or with anthralin spray, they have proven beneficial to combat psoriasis. Unfortunately, using tar can be very messy and can stain both clothing and furnishings.To avoid this, it should be applied at least 15 minutes before dressing or going to bed and wear older clothing. You will need to avoid exposing coal tar treated areas of the skin to the sun as it increases the risk of sunburn. Recently, some coal tar containing shampoos have been removed by the US authorities because of fears of increased skin cancer risk. Dithranol is a synthetic substance made from anthracene, a coal tar derivative. It takes longer to work than steroids, in many cases up to 6 weeks. It can also irritate the skin and stain everything it touches including normal skin. Skin staining is a sign that the dithranol is working. As it does not stain psoriatic skin, the staining means that the skin is clearing up. The stain should clear up a few weeks after the psoriasis itself has cleared. Dithranol is applied only to the psoriatic lesions and must be rubbed in well. Any excess should be wiped off. It must not be applied to the face or groin. It works but is a messy and often cosmetically troubling treatment.
Emollients commonly used in cream or lotion form are an important component of psoriasis therapy. They seem to slow the loss of water through the skin layers that result from frequent bathing and phototherapy sessions. The thicker the cream or lotion, the more effective the emollient is likely to be. Regular effective moisturisation can relieve the pain of dry skin and also reduce scaling and inflammation. In addition they have no side effects to worry about.
This term refers to treatment with various forms of ultraviolet light, sometimes assisted by taking particular tablets. Topical therapy will usually continue during phototherapy.
Ultraviolet (UVB) phototherapy
Also known as sun burning ultraviolet, is used to improve several skin conditions including psoriasis. The treatment involves exposing a patient to artificially generated ultraviolet light for varying lengths of time. UVB phototherapy will not cure your psoriasis, but it can effectively control or improve the disease. Nowadays narrow band UVB is used which has fewer ultraviolet wavelengths than UVB and is safer.
PUVA (UVA) phototherapy
UVA is long wavelengths of ultraviolet light and is helped by taking tablets known as Psoralens a combination known as PUVA therapy. The tablets make the skin sensitive and responsive to the light and without them the light does not treat the skin condition effectively. Long term use of PUVA therapy increases skin cancer risk. Should be reserved for severe or disabling psoriasis.
Here the psoralen drug is dissolved in bathwater in tiny amounts. The patient then receives their UVA therapy immediately after the bath. It is very effective but less practical for treatment centres to offer. There is less risk of skin cancer with bathwater PUVA compared to oral PUVA
3. Internal Treatments
For more severe or disabling psoriasis, it may be necessary to take oral medications or injections alongside your existing topical therapy or on its own.
This drug is a vitamin A derivative also known as a retinoid. It is used to treat more severe psoriasis. Patients frequently improve more when they have taken retinoids in conjunction with ultraviolet therapy than when they undergo light therapy alone.This is because the retinoid reduces the amount of ultraviolet rays needed for therapy and the combination improves the efficacy of the treatment as a whole. Acitretin therapy may last between 4-9 months and the dosage varies from person to person.
Slows down the rate at which the skin cells are dividing and has been used for psoriasis treatment longer than any other internal medication. It is usually taken once a week either orally or by injection. This drug must be used with caution. Patients must have no history of liver disease or of excessive alcohol consumption. Kidney function must also be normal so that the drug can be cleared easily from the body. You should see your doctor every 4 weeks whilst on methotrexate as there are side effects associated with this drug but most can be detected in your blood tests before they become serious.
This drug has been found to work rapidly in severe psoriasis and psoriatic arthritis.It should only be taken by patients with normal blood pressure and kidney function as it can cause raised blood pressure. Typically, cyclosporin is used to bring about a remission of psoriasis, then stopped, and maintenance therapy is continued with another treatment such as UVB, Methotrexate or Acitretin. Cyclosporin does have potential side effects. You will need to have regular monitored blood and urine tests throughout the treatment and will be stopped if any significant changes occur. Cyclosporin should not been used over prolonged periods of time because the drug suppresses the bodys immune system. Dermatologists may sometimes prescribe other drugs such as the anti cancer drugs thioguanine, fumaric acid and hydroxurea. These are all very potent drugs requiring frequent follow up appointments and blood tests.
Biological Injectable Drugs
These are a group of drugs introduced over the last 10+ years. Dr Lowe was involved in some of the first studies on these drugs and with some of the current biologics.
What are Biological Drugs ?
They are treatments produced by genetically tricking a microorganism e.g. bacteria, to produce the medicine. The biologic medicines are designed to correct some of the abnormal triggers that lead to redness (inflammation) in the skin (and joints) that then result in psoriasis. With this group of drugs the patient injects them under their skin (very like insulin in diabetes), usually weekly or monthly depending on the drug. These drugs can increase infections e.g. TB, increase in heart failure and rarely increase of internal cancers e.g. lymphoma. They must be prescribed by a Dermatologist. Finally the biologic drugs are at present very expensive and may not be covered by your private medical insurance or the NHS.