Psoriasis

Psoriasis typically looks like red or pink areas of thickened, raised, and dry skin. It classically affects areas over the elbows, knees, and scalp. Essentially any body area may be involved. It tends to be more common in areas of trauma, repeat rubbing, use, or abrasions.

Psoriasis has many different appearances. It may be small flattened bumps, large thick plaques of raised skin, red patches, and pink mildly dry skin to big flakes of dry skin that flake off.

There are several different types of psoriasis including psoriasis vulgaris (common type), guttate psoriasis (small, drop like spots), inverse psoriasis (in the folds like of the underarms, navel, and buttocks), and pustular psoriasis (liquid-filled yellowish small blisters).

Sometimes pulling of one of these small dry white flakes of skin causes a tiny blood spot on the skin. This is medically referred to as a special diagnostic sign in psoriasis called the Auspitz sign.

Genital lesions especially on the head of the penis are common. Psoriasis in moist areas like the navel or area between the buttocks (intergluteal folds) may look like flat red patches. These atypical appearances may be confused with other skin conditions like fungal infections, yeast infections, skin irritation, or bacterial Staph infections.

On the nails, it can look like very small pits (pinpoint depressions or white spots on the nail) or as larger yellowish-brown separations of the nail bed called "oil spots." Nail psoriasis may be confused with and incorrectly diagnosed as a fungal nail infection.

On the scalp, it may look like severe dandruff with dry flakes and red areas of skin. It may be difficult to tell the difference between scalp psoriasis and seborrhea (dandruff). However, the treatment is often very similar for both conditions.

http://www.medicinenet.com/psoriasis/article.htm

There are different types of psoriasis.

Plaque psoriasis

Skin lesions are red at the base and covered by silvery scales.

Also known as Classis Psoriasis or Psoriasis Vulgaris. The most common form of psoriasis, affecting about 80% of people with the disease. People with plaque psoriasis have raised, red, inflamed areas of skin-called plaques-often on the scalp, knees, elbows, chest, or back. These inflamed plaques of skin are covered by a silvery-white buildup called scale. It will often reoccur and its cause is not fully understood, although it is generally considered to be an autoimmune disease.

Pustular psoriasis

Blisters of noninfectious pus appear on the skin. Attacks of pustular psoriasis may be triggered by medications, infections, stress, or exposure to certain chemicals.

Guttate psoriasis

Small, teardrop shaped lesions appear on the trunk, limbs, and scalp. Guttate psoriasis is most often triggered by upper respiratory infections (for example, a sore throat caused by streptococcal bacteria).

The second most common form of psoriasis, characterized by small, pink or red drops on the skin. This type of psoriasis may cover a large portion of the body and is usually found on the chest, back, arms, or legs. It appears after a bacterial infection such as strep throat, especially in younger patients. Some cases go away without treatment in a few weeks, while many cases are more persistent and require treatment.

Psoriatic arthritis

Joint and connective tissue inflammation that produces symptoms of arthritis in patients who have or will develop psoriasis.
Inverse psoriasis (or "Flexural psoriasis")

Smooth, red patches occur in the folds of the skin near the genitals, under the breasts, or in the armpits. The symptoms may be worsened by friction, sweating and/or the presence of yeast or fungal infections. It is called inverse psoriasis because it occurs in moist areas, areas that aren't normally affected by classic psoriasis.

Erythrodermic psoriasis

Widespread reddening and exfoliation of the skin that may form the initial outbreak of psoriasis, but is more often the result of exacerbation of unstable plaque psoriasis, particularly under the triggering effect of: abrupt withdrawal of systemic treatment, use of systemic steroids or excessive use of high potency topical steroids corticosteroids (cortisone) or in a koebner response to a widespread allergic reaction or severe sunburn. This form of psoriasis can be genuinely dangerous, since the extreme inflammation and exfoliation interfere with the body's ability to regulate temperature and perform other barrier functions.

source :http://herbalpsoriasistreatment.com

There are several forms of psoriasis, including plaque, guttate, scalp, inverse, nail, pustular, and erythrodermic psoriasis. General symptoms can include: red patchy skin with silvery scales, scaly spots, dry and cracked skin that can bleed, itching, burning, soreness, and swollen and stiff joints.

From eHealthMD:

Evidence from recent research studies strongly suggests that psoriasis is a disorder of the immune system. Normally, the immune system defends the body from infection by bacteria, viruses, and other invaders. Sometimes, however, the immune system makes a mistake and attacks the cells, tissues, and organs of a person's own body. When this happens, the resulting disease is called an autoimmune disease. Many autoimmune diseases run in families.The theory that psoriasis is an autoimmune disease is based on the fact that scientists have found abnormally large numbers of T cells (a type of white blood cell) in the red, flaky skin patches of people with psoriasis. T cells are the infantry of the immune system. When the body senses a need to defend itself against infection, it first makes and then releases millions of T cells to fight off the invaders. Some t cells are normally found in skin. The presence of abnormally large numbers of T cells in skin affected by psoriasis suggests that the immune system is attacking the skin by mistake.(http://www.ehealthmd.com/library/psoriasis/pso_causes.html)