Psoriasis is a condition that is caused by an over-active immune system. With psoriasis, the immune system mistakes normal skin cells as something foreign and attacks them. This immune response causes the skin cells to divide very rapidly, causing them to build up on the skin's surface. There are five major types of psoriasis with each kind having their own characteristic lesions and symptoms.
Plaque Psoriasis
Plaque psoriasis makes up approximately 80 percent of all cases of psoriasis. Plaque psoriasis is marked by thickened and raised patches of skin, which are called plaques. These plaques are red and generally appear on the knees, elbows, scalp, lower back and chest. They begin as small red bumps and gradually get bigger and then are topped with silvery scales. The plaques generally itch and may also burn. The skin on the plaques may also crack and bleed.
Pustular Psoriasis
Pustular psoriasis can develop from plaque psoriasis, or can appear by itself. Pustular psoriasis gets its name from the lesions filled with pus that dot the red and swollen skin. When these lesions dry out they leave behind small brown spots. Although pustular psoriasis usually occurs on the soles of the feet and on the palms, in some cases it can cover the body, leading to a serious and life-threatening condition.
Guttate Psoriasis
The primary symptom of guttate psoriasis is the development of small red lesions in the shape of a teardrop. These lesions most commonly occur on the legs, arms and trunk, although they can appear elsewhere on the body (face, scalp and ears). Although mild cases may disappear without treatment, more severe cases may require oral or injected corticosteroids.
Erythrodermic Psoriasis
Although the least common form of psoriasis, erythodermic psoriasis is a very serious condition because it disrupts the skin's ability to serve as a protective barrier. This form of psoriasis is marked by the development of large patches of skin that are very red (like they have been burned). These patches may itch or be painful and can cause rapid fluctuations in body temperature.
Inverse Psoriasis
Inverse psoriasis is a form that does not cause scales to form because it only affects skin folds (such as the armpits, under the breasts, and the genital and buttock area). This type of psoriasis is typically very tender and is easily irritated by rubbing or friction. It most commonly affects people who are overweight.
