Psoriatic arthritis

The exact causes of psoriasis are not fully known, but studies show that the immune system plays a central role. It is believed that the immune system mistakenly activates a type of white blood cell known as T cells. Activated T cells trigger inflammation, which causes the skin to renew itself more rapidly. Under normal conditions, the skin renews itself within 30 days. If this process is accelerated and the skin renews itself within 3 to 4 days, psoriasis develops.

Usually, a triggering factor is needed for psoriasis to start, for example:

• Stress;
• Infection, such as streptococcal throat infection;
• Use of certain medications, such as interferon and lithium;
• Cold and dry winter weather;
• Lack of sunlight;
• Skin injury, such as a cut, scratch, or severe sunburn — in these cases, the development of the disease is known as the Koebner phenomenon.

There are five main types of psoriasis, each with its own distinctive signs and symptoms:

• Plaque psoriasis. This is the most common type. It is characterised by raised, reddish patches covered with a silvery-white surface. The patches most often appear on the elbows and knees, lower back, and scalp, although they may also appear elsewhere.
• Guttate psoriasis. This type of psoriasis is most common in children and young adults. It is characterised by the appearance of small red spots on the skin. Guttate psoriasis is often seen after a throat infection and may disappear on its own within a few weeks or months.
• Pustular psoriasis. This type is characterised by white, pus-filled lesions (pustules) surrounded by red skin. It tends to appear on specific areas of the body, mainly on the palms and soles. In these cases, it is called localised pustular psoriasis. If the disease spreads to other, larger areas of the skin, it is called generalised pustular psoriasis. This is a rare and very severe form of the disease that may even be life-threatening.
• Inverse psoriasis. This form causes smooth, red rashes in skin folds, such as the armpits, under the breasts, around the groin, buttocks, and genitals.
• Erythrodermic psoriasis. In this case, widespread redness develops over the whole body, causing severe itching and pain. Erythrodermic psoriasis may be life-threatening.

Psoriasis often appears on the scalp and nails. When psoriasis affects the scalp, it is covered with a silvery-white surface and may therefore be mistaken for dandruff. Psoriatic nails often have small pits. The nails may become thinner, thicker, or crumble. These signs may be confused with nail infections. Psoriasis of the scalp and nails is among the most difficult forms to treat.

Approximately 10% to 30% of people with psoriasis have a disease-related form of arthritis called “psoriatic arthritis”, which causes joint inflammation. Psoriatic arthritis is a lifelong condition that causes changes, pain, and stiffness in the joints. Medication can help prevent joint deformities and disability if started in time. Without appropriate treatment, permanent joint deformity and destruction may occur.

To diagnose psoriasis, dermatologists examine the skin, nails, and scalp. A skin biopsy may also be used to confirm the diagnosis.

Psoriasis cannot be completely cured, but it can be controlled using various methods. The choice of suitable treatment depends on:

• The patient’s health condition;
• Age;
• Lifestyle;
• The stage of psoriasis.

Different treatment methods and repeated visits to a dermatologist may be needed to control the disease. To help patients manage psoriasis, a dermatologist may prescribe topical medicines applied externally to the skin surface in the areas affected by the disease. In addition to these medicines, the doctor may also prescribe natural sunlight therapy or other ultraviolet (UV) light therapy. More severe forms of psoriasis may also require oral or injectable medicines.

Topical medicines:

• Corticosteroids (cortisone). Cortisone reduces inflammation. Cortisone creams, ointments, and lotions can clear the skin in the short term and help many patients control the disease. Milder preparations should be used on more sensitive areas of the body, such as the genitals, armpits, or face. Stronger preparations are needed to control inflammation on the scalp, elbows, knees, palms, soles, and other areas. Dressings may be used to improve the effect of the medicine. Corticosteroid injections may be used for rashes that are difficult to treat. Corticosteroids must be used cautiously and only according to the dermatologist’s instructions. Side effects of stronger cortisone preparations include changes in skin colour, stretch marks, prominent blood vessels, and thinning of the skin. If these medicines are stopped suddenly, the disease may flare up. If cortisone has been used for many months, psoriasis may become insensitive (resistant) to it.
• Anthralin. Anthralin is effective for thick psoriasis plaques that are difficult to treat; it also slows skin overgrowth and reduces inflammation. Newer preparations and treatment methods reduce the usual side effects — skin irritation and staining.
• Calcipotriene. Suitable for patients with localised psoriasis. Calcipotriene may be combined with other treatment methods. To avoid side effects, such as skin inflammation, calcipotriene should be used only according to a dermatologist’s instructions.
• Retinoids. These medicines are used to treat localised psoriasis. They may be used alone or together with topical corticosteroids. Retinoids should not be used by women who are planning to become pregnant.
• Coal tar. Coal tar has been used safely and effectively to treat psoriasis for more than 100 years. Modern products have been significantly improved and are easier to use. Stronger preparations may be used on areas that are difficult to treat.

Oral medicines — systemic treatment agents:

• Retinoids. In severe psoriasis, oral retinoid medicines may be prescribed alone or in combination with ultraviolet light therapy. Possible side effects include dryness of the skin, lips, and eyes; increased fat levels in blood tests (cholesterol and triglycerides); and the formation of osteophytes (small bony growths). Pregnant women or women planning pregnancy should not use retinoids. These medicines may have an adverse effect on pregnancy for 3 years after treatment has ended. Patients taking retinoids need regular examinations and blood tests.
• Cyclosporine. This medicine suppresses the immune system and is used to prevent rejection of transplanted organs, for example after liver or kidney transplantation. Although cyclosporine is an extremely effective treatment for psoriasis, it is used only in very severe cases where the disease has not responded to other treatment methods. Because of possible side effects, patients must have their liver condition and blood pressure checked before starting the medicine. Patients taking cyclosporine need regular examinations and blood tests.

In addition to these medicines, biological agents are also used. These are systemic medicines administered by injection or infusion. Biological agents are unique because they target specific immune system responses involved in the treatment of psoriasis. For this reason, it is especially important to consult a dermatologist, as there are different treatment methods and combinations, and various tests must be performed before the most suitable treatment method can be determined. The group of biological agents used to treat psoriasis includes:

• Alefacept. It is used in moderate to severe psoriasis with chronic inflammation to block activated T cells. Treatment with alefacept consists of intramuscular injections performed by a healthcare professional, allowing the medicine to reach deep into the large muscles of the body. Patients usually receive one injection per week for 12 weeks.
• Etanercept. This biological agent is used to treat psoriasis and psoriatic arthritis. It blocks a signalling substance in the body called tumour necrosis factor alpha, or TNF-α, which causes cells to trigger inflammation and thereby also causes psoriasis. Etanercept is administered by subcutaneous injections, which patients may perform themselves. Etanercept is usually used as part of long-term therapy.
• Efalizumab. To treat psoriasis, this biological agent prevents the activation of T cells. If T cells are not activated, psoriasis may improve. It is intended as long-term therapy, and patients can learn to administer the injections themselves.
• Infliximab. To treat psoriasis and psoriatic arthritis, this biological medicine blocks TNF-α. Since it is administered by infusion, the procedure must be performed in a professional medical institution.
• Adalimumab. This biological agent blocks TNF-α and is an effective treatment for psoriatic arthritis. Adalimumab is administered by subcutaneous injections, which patients can learn to perform themselves.

An effective and proven treatment for psoriasis is light therapy, or phototherapy. Ultraviolet (UV) rays found in sunlight slow the growth of skin cells. Light therapy procedures for patients with psoriasis may be performed in a dermatologist’s office, a psoriasis centre, or a hospital. Patients with psoriasis who live in warm climates should sunbathe carefully. Under the supervision of a dermatologist, light therapy offers patients a safe and effective treatment method. However, caution is required with UV rays, so therapy should not be started on one’s own initiative without medical guidance. Professional medical centres offer patients the following types of phototherapy:

• UVB light therapy. During this therapy, the skin is exposed to ultraviolet rays in the medium-wavelength range (UVB). The therapy may be used alone or in combination with other topical or systemic treatment methods. During UVB therapy, the patient may enter a light booth that surrounds them or stand in front of a light panel. Approximately 24 sessions over two months are needed for improvement. Although UVB is a very safe and effective treatment method, side effects such as burns, the appearance of freckles, or premature skin ageing are possible. The risk of skin cancer is no greater than from sun exposure.
• PUVA. The abbreviation PUVA stands for “psoralen and ultraviolet A (UVA) radiation”, which are the two components of this treatment method. PUVA is an effective method in approximately 85% of cases and is used for widespread psoriasis and when the disease has not responded to other treatment methods. Before PUVA, the patient receives psoralen medicine orally or externally. The patient is then exposed to ultraviolet A rays in a carefully determined dose. Since psoralen can accumulate in the lenses of the eyes, patients must wear UVA-blocking glasses when exposed to sunlight from the time psoralen medicine is taken until the evening of that day. Improvement usually appears after approximately 25 PUVA sessions over two to three months. To control psoriasis, approximately 30 to 40 sessions per year are needed. Over a long period, PUVA therapy reduces the risk of premature ageing, spot formation, and skin cancer. Dermatologists monitor PUVA therapy very carefully.
• Goeckerman therapy. This is named after the Mayo Clinic dermatologist who first described it. This treatment method combines the use of coal tar with UV rays. The method is used in severe cases of psoriasis. It is performed over a defined period of time, repeated once daily. Exposure to UV rays depends on the type of psoriasis and the sensitivity of the patient’s skin. Access to this treatment method is limited because only a few specialised centres in the USA offer it.

Possible symptoms of psoriatic arthritis:

• Raised, reddish patches covered with a silvery-white surface
• Appearance of small red spots on the skin
• White, pus-filled lesions (pustules) surrounded by red skin
• Red rashes in areas where the skin folds
• Redness across the whole body causing pain and itching