Psoriasis is defined as a skin disease with no clear cause or cure.It can show up as raised, red, scaly patches on the skin and can result in inflammation. The main five types of psoriasis are the plaque psoriasis, guttate psoriasis, inverse psoriasis, pustular psoriasis, and erythrodermic psoriasis.

The exact reason behind the occurrence of psoriasis is not fully understood yet. A combination of the genes that cause psoriasis and exposure to specific external factors known as “triggers” can make a person more likely to develop psoriasis. Triggers include infections, stress, skin injury, and certain drugs.

Some of the risk factors associated with psoriasis include family history, viral and bacterial infections, and obesity. Although the exact mechanism behind the psoriasis occurrence still not fully determined, it is thought to be an immune system related problem.

Basically, the disease starts in the immune system; mainly with a type of white blood cell known as a T cell. T cells are well known as protectors against infection and disease. When psoriasis occurs, T cells start functioning by mistake. They become so functional to the point that they set off other immune responses

The main symptom associated with psoriasis is flaky, red, irritated patches of skin. Other symptoms may include dry, itchy, raised, and thick skin.

To diagnose psoriasis properly, a doctor may review the family history and the medical history of the patient.Also, the doctor may examine the skin to looks for signs of psoriasis. Unfortunately, there is no definitive treatment for psoriasis; a patient is only able to manage symptoms.

There are three treatment options available, the first one is the treatments which used on the skin (topical) such as creams and ointments, the second one is systemic (body-wide) treatments which use medications, the third one is phototherapy treatment (light therapy).

Critical health complications may develop if psoriasis does not manage properly. These complications may include particular eye conditions, diabetes, high blood pressure, and emotional problems.

There is no definitive method to prevent psoriasis from occurrence. Cleaning the skin, using moisturizers, and avoiding psoriasis triggers may help decrease attacks number.

From an epidemiological standpoint, The prevalence of the disease has been studied only in 20 countries around the world, the prevalence studies varied from 0.09% in the United Republic of Tanzania to 11.4% in Norway. In addition, psoriasis is more common to occur in northern Europe countries and least common to occur among populations of eastern Asia.

Psoriasis is a skin, noncommunicable, immune-mediated, painful disease with no clear cause or cure that may result in raised, red, scaly patches to appear on the skin and can causes and inflammation.

Also, it can be classified as a common chronic condition that responsible for emerging of thick red marks and flaky white patches that look like scales to form on the skin. If psoriasis developed in more than 10 % of the body, then, it will be considered severe condition.

Mainly, there are five types of psoriasis which can be studied separately in the medical literature. Those types can be summarized in the following:

• Plaque psoriasis: Also called psoriasis vulgaris, is more common than the other types of the disease and the appearance of this type can take the form of raised, red patches covered with a silvery white formation of dead skin cells or scales. Most of the time, these patches or plaques can be seen on the scalp, knees, elbows and lower back.
• Guttate psoriasis: This is the second most common type of psoriasis, about 10 % of people who get psoriasis develop guttate psoriasis particularly, and mostly it starts in childhood or in young adulthood. The appearance of this type can take the form of small, red, separate spots on the skin. This form is capable to co-exist with other forms of psoriasis, such as plaque.
• Inverse psoriasis: Also called flexural psoriasis or intertriginous psoriasis, appears smooth and shiny and can take the form of very red lesions in body folds. Overweight people and people with deep skin folds are more susceptible to have this form of psoriasis. This form of psoriasis might develop along with another type of psoriasis elsewhere on the body at the same time. The possible body locations that can develop inverse psoriasis include armpits, groin, under the breasts and in other skin folds. Curing this form of psoriasis can be challenging due to the sensitivity of the skin in these areas.
• Pustular psoriasis: This form of psoriasis is seen in adults particularly and shows up as white blisters of noninfectious pus surrounded by red skin. It is not an infectious or contagious condition. The released pus consists mostly of white blood cells. The distribution of this form is limited to certain areas of the body, for example, the hands and feet. The three major types of pustular psoriasis include :

1. Von Zumbusch: This form of pustular psoriasis can show up as a sudden widespread area of painful and tender reddened skin. The development of this form of pustular psoriasis can results in fever, dehydration, chills, anemia, muscle weakness, severe itching, a rapid pulse rate, exhaustion, and weight loss. This form can be life-threatening and requires immediate medical care.
2. Palmoplantar pustulosis: This form of pustular psoriasis is responsible for showing pustules on the palms of the hand and soles of the feet. The common affected sites are the base of the thumb and the sides of the heels.
3. Acropustulosis: This form of pustular psoriasis shows up skin lesions on the ends of the fingers and sometimes on the toes.Also, certain bone changes may develop in critical cases.

• Erythrodermic psoriasis: Also called exfoliative psoriasis. This is a rare type of psoriasis, which may affect most of the body surface and is considered as an inflammatory form of psoriasis. The occurrence of this form of psoriasis may relate to von Zumbusch pustular psoriasis, also, it is may appear once or more during the lifetime of 3 % of people who have psoriasis. Erythrodermic psoriasis causes protein and fluid loss that can lead to severe illness. Edema (especially around the ankles), infection, shivering episodes, pneumonia and congestive heart failure are all may developed once erythrodermic psoriasis occurs. Hospitalization may require for severe cases.

In addition to the mentioned types, there is another type, which related to psoriasis called “psoriatic arthritis”. Psoriatic arthritis results in swollen, painful joints as well as inflamed, scaly skin. Symptoms of psoriatic arthritis are range from mild to severe; also, psoriatic arthritis can affect any joint in the body.

The exact reason behind the occurrence of psoriasis is not fully understood yet. However, researchers confirm that a person’s immune system and genes play important roles in the occurrence of psoriasis.

About 25 genetic variants are identified by researchers. Those genetic variants make a person more susceptible to develop a psoriatic disease. A combination of the genes that cause psoriasis and exposure to specific external factors known as “triggers” can make a person more likely to develop psoriasis.

Things that can trigger psoriasis include:

• Infections: Things that can alter the immune system can affect psoriasis. For instance, guttate psoriasis is associated with streptococcus infection (strep throat).
• Stress: Stressors can trigger psoriasis to develop for the first time or it can worsen an existing psoriasis.
• Skin injury: Koebner phenomenon is when psoriasis shows up on damaged or injured regions of skin. Several factors such as vaccinations, sunburns, and scratches may trigger the phenomenon.
• Certain medications such as Lithium, antimalarials, inderal, quinidine, and indomethacin.
• Changes in weather that dry the skin
• Drinking too much alcohol
• Vitamin D deficiency
• Smoking

In addition, psoriasis is not a contagious type of disease and the person cannot develop psoriasis merely from swimming in the same pool or from having sexual intercourse.

Anyone can develop psoriasis, but the following factors may increase the risk of having psoriasis include:

• Family history: Presence of one parent with psoriasis may raise the possibility of developing psoriasis for the child, and presence of two parents with the disease may increases the risk even more.
• Infections: The possibility of developing psoriasis increases in children and young adults who suffer from recurring infections whether viral and bacterial (particularly strep throat). In addition, HIV infected persons are more susceptible to develop psoriasis than people with healthy immune systems.
• Smoking: Smoking may trigger the initial development of the disease and may increase the severity of the disease in the later stages.Therefore smoking tobacco increases the risk of psoriasis and it is not advisable to continue smoking.
• Stress: High levels of stress may increase the risk of developing psoriasis because of stress consequences in the immune system.
• Obesity: Lesions that may appear in most types of psoriasis often develop in skin creases and folds. Therefore, excess weight is undesirable and it may increase the risk of developing psoriasis.

In the normal circumstances, skin cells are made and replaced every three to four weeks. People with psoriasis have an increasing and abnormal production of skin cells.In case of psoriasis, the process of creating and replacing skin cells only lasts about three to seven days. Skin cells formations that resulted from this recurrent process are what create the patches associated with psoriasis.

Although the exact mechanism behind the occurrence of the process still not fully determined, it is thought to be an immune system related problem. Indeed, the disease starts in the immune system, mainly with a type of white blood cell known as a T cell.

T cells are well known as protectors against infection and disease. When psoriasis occurs, T cells start functioning by mistake. They become so functional to the point that they set off other immune responses. This action will result in swelling and fast turnover of skin cells.

The role of genetics in causing psoriasis is not fully understood yet. Evidence-based studies identified several genes associated with the development of psoriasis. It is probable that different combinations of genes may play a role in making individuals more susceptible to develop the disease. However, having these genes does not mean developing the disease is fated.

The main symptom associated with psoriasis is flaky, red, irritated patches of skin. Plaques are the common medical term for the observed patches. When psoriasis occurs, the skin may be:

• Dry and covered with silver, flaky skin (scales)
• Itchy , raised and thick
• Pink-red in color (like the color of salmon)

Other symptoms associated with psoriasis may include:

• Nail changes such as thick nails and lifting of the nail from the skin underneath
• Critical presence of dandruff (on the scalp)
• Sores in the genital area in males and painful joints in both males and females.

In order to diagnose psoriasis, a dermatologist may perform certain steps include:

• Reviewing the family history by asking for instance whether family members have psoriasis.
• Reviewing the medical history of the patient by investigating about what has been happening in the life of a patient life, whether a patient has been under a lot of stress, had a recent illness, or just started taking a medication.
• Examines skin, nails, and scalp of the patient to look for signs of psoriasis.

In addition, a skin biopsy may be recommended to distinguish other possible conditions. If the patient complains about joint pain, a physician may recommend X-rays.

There is no definitive treatment for psoriasis, a patient is only able to prevent or manage symptoms. Changes in lifestyle, such as skin moisturizing, quitting smoking and effective stress management, may be useful. However, treatment of psoriasis depends on:

• Disease’s level of intensity
• Size of the observed patches
• Psoriasis type
• The reaction of the patient’s body to the given drugs

The goal of the used treatment is to control the symptoms and prevent infection. There are three main treatment options available to manage psoriasis, these are:

1. Treatments used on the skin (topical): Psoriasis is treated often by using medications that are placed directly on the skin or scalp such as:

• Creams or ointments that contain cortisone
• Creams or ointments that contain coal tar or anthralin
• Salicylic acid or lactic acid creams that used to remove the scaling
• Prescribed or over the counter dandruff shampoos
• Skin moisturizers
• Calcineurin inhibitors that used reduce inflammation and plaque buildup.

1. Systemic (body-wide) treatments: In case of severe psoriasis, physicians usually recommend medications that work in weakening the faulty response of the immune system. These medications include methotrexate which decreases the production of skin cells and suppressing inflammation or cyclosporine which have a similar action to methotrexate but can only be taken for short-term. In addition, medications that related to vitamin A such as retinoids can be used. Newer drugs called biologics are used when other treatments do not work. Biologics approved for the treatment of psoriasis include:

• Adalimumab (Humira)
• Etanercept (Enbrel)
• Infliximab (Remicade)
• Ustekinumab (Stelara)
• Secukinumab (Cosentyx)
• Apremilast (Otezla)
• Ixekizumab (Taltz)

Most of biologics are given by injection except apremilast given orally. Biologics usually recommended for people who do not show any positive response to traditional therapy or who developed psoriatic arthritis.

Phototherapy treatment (light therapy): The mechanism of this therapy is simply applied by skin exposure to ultraviolet light. Natural or artificial ultraviolet light sources could be used in conducting this type of treatment. The modes of light therapy include.

• Sunlight: Slowing skin cell turnover and reduces scaling and inflammation may be resulted from the exposure to ultraviolet (UV) rays in sunlight or artificial light.
• Ultraviolet  B )UVB( phototherapy: Also known as broadband UVB, can be applied in treating single patches, widespread psoriasis, and psoriasis that does not respond to topical treatments.
• Narrow band UVB phototherapy: A narrow band UVB phototherapy may be considered more effective than broadband UVB treatment and newer but may lead to more-severe burns.
• Goeckerman therapy: Using UVB treatment and coal tar treatment together is called Goeckerman treatment.
• Psoralen plus ultraviolet A (PUVA): This form of photochemotherapy in which light-sensitizing drug (psoralen) should be taken before exposure to UVA light. Psoralen help make the skin more responsive to UVA exposure.
• Excimer laser: In this mode of light therapy, the treatment is only targeting damaged skin without harming healthy skin and it is only used to treat mild to moderate psoriasis.

Alternative medicine: Several alternative therapies claim to ease the symptoms of psoriasis but it is fair to say that none of those therapies has definitively been proved effective including special diets, creams, dietary supplements, and herbs. Some alternative therapies are considered safe in the general sense include:

• Aloe vera: This is the product which taken popularly from leaves of the aloe vera plant, aloe vera cream may help reduce redness, inflammation, scaling, and itching.
• Fish oil: Although results from studies are mixed, Omega-3 fatty acids may help reduce inflammation associated with psoriasis. Omega-3 fatty acids found mainly in fish oil supplements.
• Oregon grape: Topical use of Oregon grape may help reduce inflammation and ease psoriasis symptoms. This fruit is called barberry as well.

Other treatments: For instance, if the infection is triggering psoriasis, a physician may prescribe antibiotics.

Having psoriasis may increase the risk of developing more critical health conditions. These include:

• Eye problems: Psoriasis can increase the risk of developing several eye disorders include conjunctivitis, blepharitis, and uveitis.
• Obesity: There is a noticeable tendency for individuals with psoriasis to be obese or overweight. Still, there is no clear explanation why this occurs. However, inflammation linked to obesity or the inactiveness of individuals with psoriasis may be considered as possible reasons standing behind this occurrence.
• Type 2 diabetes: The more severe psoriasis, the greater the chance of developing type 2 diabetes.
• High blood pressure: The possibility of developing high blood pressure increases in individuals with psoriasis.
• Cardiovascular disease: The possibility of developing the cardiovascular disease is doubled in individuals with psoriasis. Irregular heartbeat, stroke, high cholesterol, and atherosclerosis are all associated with psoriasis.
• Metabolic syndrome: This is involving a group of conditions including abnormal cholesterol levels, elevated blood pressure, and elevated insulin levels. This condition increases the possibility of developing heart disease.
• Other autoimmune diseases: An inflammatory bowel disease called Crohn's disease, celiac disease, and sclerosis are more probable to appear in people with psoriasis.
• Parkinson's disease. People with psoriasis are more susceptible to develop this chronic neurological condition.
• Kidney disease: Higher risk of kidney disease has been associated with moderate-severe psoriasis.
• Emotional problems. Low self-esteem, depression, and social isolation have been linked to psoriasis.
• Psoriatic arthritis: This disorder can cause weakening of joints and a loss of function in some others.

There is no definitive method to prevent psoriasis from occurrence. Cleaning the skin, using skin moisturizers, and avoiding psoriasis triggers may help decrease attacks number. Doctors may suggest daily baths or showers for people with psoriasis. Scrubbing the skin hardly is not advisable because this can hurt the skin and can cause a flare up an attack.

Psoriasis cannot be cured and basically considered as one of the chronic (long-lasting) diseases of the immune system. Psoriasis can be controlled with treatment through one’s lifetime.

It may disappear for quite some time and reappear again. Using appropriate treatment for psoriasis will not cause other problems to the body. However, the awareness of the strong correlation between psoriasis and other health problems, such as heart disease should be considered.

For the affected region of the skin to return to more normal thickness, it may take 2 to 6 weeks and the redness may take several months to improve. Certain scaly spots may show improvement on some occasions but other spots may get worse.

• The followings are psoriasis-related facts reported by WHO :

1. The prevalence of the disease has been studied only in 20 countries around the world, the prevalence studies varied from 0.09% in the United Republic of Tanzania to 11.4% in Norway. 
2. Prevalence of psoriasis in most developed countries is between 1.5 and 5%.
3. Psoriasis is more common to occur in northern Europe countries and least common to occur among populations of eastern Asia.
4. The prevalence of psoriasis in China in 1984 reported as 0.17%, while 25 years later, another study conducted and reported the prevalence increased to 0.59 %.The prevalence in Spain in 1998 was 1.43%, while 15 years later, the figure increased to be 2.31%.
5. The incidence of psoriasis in Algeria, Tunisia, and Morocco was estimated at 10.36, 13.26 and 15.04 per 1000, respectively.

• The following are psoriasis-related facts reported by the National Psoriasis Foundation in the United States:

1. Approximately, 20,000 children under 10 years of age are diagnosed with psoriasis annually.
2. 2 to 3 % of the population develops psoriasis.
3. If one parent developed psoriasis, the child chance to have the disease become 10 %.
4. About 11 % of people diagnosed with psoriasis have also been diagnosed with psoriatic arthritis.

• According to the American Academy of Dermatology, In the United States, about 7.5 million people have psoriasis. About 80% of them have plaque psoriasis. Most people develop psoriasis between 15 and 30 years of age. Between 50 and 60 years of age is another common time for psoriasis to begin. In addition, Caucasians get psoriasis more often than other races.
• According to a study published in the Journal of Investigative Dermatology, the prevalence of psoriasis in children ranged from 0% in Taiwan to 2.1% in Italy, and in adults; it varied from 0.91% in the United States to 8.5% in Norway. In addition, the study confirms that the occurrence of psoriasis is more frequent in countries which more distant from the equator.