Psoriasis

Psoriasis is an inflammatory skin disease in which skin cells divide rapidly and produce cells. New skin cells are produced about eight times faster than normal but the rate at which old cells get rid of is unchanged.
This causes cells to build up on the skin's surface, forming thick patches, or plaques, of red sores (lesions) covered with flaky, silvery-white dead skin cells (scales).
They may appear anywhere, but mostly appear on the scalp, elbows, knees, and lower back.
Psoriasis is not contagious. It can't be passed from person to person.
It is long-lasting autoimmune disease that(meaning that part of the body's own immune system becomes overactive and attacks normal tissues in the body.) affects two to four percent of the population.
Both Men and women are affected with equal frequency and it may begin at any age. Psoriasis is a chronic condition which tends to run in families.
Types of Psoriasis
There are several types of Psoriasis and some of these are,
Plaque psoriasis (psoriasis vulgaris) is the most common form of psoriasis. It affects 80 to 90% of people with psoriasis. Plaque psoriasis typically appears as raised areas of inflamed skin covered with silvery white scaly skin. These areas are called plaques.
It is characterised by scaly pink patches commonly appearing on the elbows, knees shins and scalp; fingernails and toenails are also often affected. On light skin, this usually shows as raised, inflamed, red lesions that are covered by silvery-white scales. On dark skin, it presents as purple or dark brown patches with gray scales.
Flexural or Inverse psoriasis develops in skin folds and it commonly affects the armpits, the groin, the areas under the breasts and other skin folds, such as those around the genitals and buttocks.
Inverse psoriasis produces lesions without the scales that might be smooth and shiny.
This type of psoriasis can be caused due to the irritation from rubbing and sweating and it is more common among people who are overweight and those with deep skin folds.
Erythrodermic psoriasis is rare and affects around 1% to 2.25% of people with psoriasis.
Some people who have severe plaque psoriasis, it may turn into erythrodermic psoriasis.
A person with erythrodermic psoriasis may experience severe inflammation, severe itching, pain, and large-scale skin shedding.
It may also cause edema, or swelling from fluid retention, especially around the ankles.
Other symptoms include changes in heart rate and temperature, dehydration and nail changes.
The complications of erythrodermic psoriasis can be dangerous. So, it is important to see a health care provider immediately
Guttate psoriasis is more common in children and adolescents than adults. It affects nearly 8 percent of people living with psoriasis.
Guttate psoriasis often appears as small, round, red spots caused by inflammation on the arms, legs and torso.
Pustular psoriasis affects about 3 percent of people living with psoriasis. It  appears as white pustules, or blisters of pus, surrounded by inflamed skin. It can affect specific areas of the body, such as the hands and feet or cover most of the skin’s surface. The pus is noninfectious, but can cause flu-like symptoms such as, fever, chills, rapid pulse, muscle weakness, loss of appetite.

People with psoriasis may also suffer from psoriatic arthritis, scalp psoriasis and nail psoriasis.
Psoriatic arthritis can affect many joints  causing joint inflammation with symptoms of arthritis.
Nail psoriasis is more common in people who have psoriatic arthritis and it can cause nail pitting, grooves, discoloration, loosening or crumbling of nail, thickened skin under nail, colored patches or spots under nail.
Scalp psoriasis is common in people with plaque psoriasis and it may cause severe dandruff which  can be painful, itchy, and noticeable at the hairline. It can extend to the neck, face, and ears in one large patch or many smaller patches. Excessive scratching can cause hair loss and scalp infections.