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Psoriasis is a common and lifelong skin disorder that causes thick crusty patches covered with white or silvery scales. It is a global health challenge, affecting over 125 million people worldwide. In Hong Kong, approximately 0.3% of the population, i.e. more than 20,000 people, are living with this disease. You may wonder why it affects relatively fewer people in Hong Kong compared to the rest of the world. The good news is that there are only 10 out of 44 known genes related to psoriasis which are found in Chinese ethnicity.
Psoriasis is a chronic, autoimmune skin condition that increases the rate of skin cell production. The normal life cycle of skin cells is about one month. However in psoriasis, this process takes only less than a week, resulting in overproduction and buildup of cells on the skin surface. This is why raised red patches and thick scales that can be painful, itch, crack and flake off are commonly seen.
Psoriasis is typically present on elbows, knees and scalp, particularly at the hairline. It can also appear on the face, hands, neck, ear canals, nails and genital areas. In most cases, it only covers a few small areas, while it can be widespread for some people.
People at any age can develop psoriasis, however it is more common in people aged 15-25, and in their fifties. Generally speaking, psoriasis affects a larger area and brings more serious impacts if it starts earlier in life. Psoriasis is not contagious. Both men and women carry equal risk of getting it.
Until now, there is no complete cure but it is controllable. Psoriasis comes and goes. Sometimes the symptoms can be severe, then they may disappear before flaring up again.
It can be hard to tell psoriasis and eczema apart as some of their symptoms overlap. However, the former is usually characterized by thick patches with flaking white scales. The boundary of the patches are sharply demarcated. As for eczema, it mostly presents as very dry skin with thinner red patches with ill-defined edges. Oozing can occur sometimes. The locations of affected skin areas are different as well.
Check out our complete guide to eczema:
Psoriasis comes in many types. Although people commonly only have one type at a time, it is possible for two types to appear simultaneously.
The signs and symptoms of psoriasis vary with the type, location and area involved. The most common ones are:
The exact causes of psoriasis are still unclear. However, it is largely related to issues in the immune system. T cells, a type of white blood cells, target and kill the normal skin cells wrongly. This speeds up the growth rate of skin cells. The new ones push themselves upwards while the falling off of old skin cells cannot catch up with the production pace. This results in accumulation and formation of thick patches with scales.
Other risk factors and triggers include:
Psoriasis is often associated with the following complications:
Your doctor may diagnose psoriasis by either physical examination or microscopic examination of a sample of the affected skin. He/she may also review your family history as it is one of the risk factors, and ask you some questions to find out any possible triggers.
Treatment options depend on the type, location and severity which can be mild (<3% of the body surface is affected), moderate (3%-10%) or severe (>10%). They do not provide a cure but can be effective.
Topical agents (for mild and moderate disease)
Systemic agents (for moderate to severe disease)
Phototherapy is exposing our skin regularly to ultraviolet light to treat moderate to severe psoriasis. Psoralen (a naturally occurring substance in many plants that absorbs UV light) with ultraviolet A (PUVA), UVB and narrow-band UVB therapy are available. UVB can be used in a combined treatment with coal tar.
They are a new class or drugs reserved for patients unresponsive to other treatments. They can be very effective but expensive. They target substances involved in inflammation.
A rheumatologist is a licensed medical doctor specializing in rheumatic diseases i.e. diseases of the joints, bones and muscles. One common type of psoriasis is psoriatic arthritis, so a rheumatologist can provide professional treatment and advice in managing it.
An internist is similar to a general physician but receives more specialized training. They can also provide diagnosis and treatment for other health issues related to psoriasis.
Sometimes patients may need a psychologist to take care of their mental health as psoriasis affects appearance which could affect one’s self-image and self-esteem, affecting mental well-being if it is not managed properly in the long run.
To date, there is no cure for psoriasis. Nonetheless, a number of topical agents, systemic agents, biologic agents and photochemotherapy are proved to be effective in alleviating the symptoms.
Elbows, knees and scalp are the usual locations where psoriasis appears. Psoriasis can also be present on the face, hands, neck, ear canals, nails as well as genitals.
Psoriasis appears as thick crusty patches with flaking white or silvery scales on the skin.
Though some symptoms of psoriasis and eczema overlap, you can distinguish the two by differentiating the appearance of the skin patches. For psoriasis, the edges of the patches are usually sharply defined; eczema, on the other hand, appears as thinner dry red patches with unclear boundaries.
This article was medically reviewed by Dr. Nicola Chan 陳珮瑤醫生. Dr. Nicola Chan is a Specialist in Dermatology in private practice, based in Hong Kong. She graduated from the University of Cambridge, UK, and received post-graduate medical training in Cambridge, London and Hong Kong. This was followed by further laser and aesthetic dermatology training in Boston and Baltimore, USA. Dr. Chan is a member of the Hong Kong Society of Dermatology and Venereology, American Society of Laser Medicine and Surgery, Asian Dermatological Association, and Hong Kong College of Dermatologists.
This article was independently written by Healthy Matters. It is informative only and not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be relied upon for specific medical advice.
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