Psoriasis

Psoriasis is a non-contagious common skin condition that causes rapid skin cell reproduction resulting in red, dry patches of thickened skin. The dry flakes and skin scales result from the rapid buildup of skin cells. Psoriasis commonly affects the skin of the elbows, knees, and scalp It commonly causes red, scaly patches to appear on the skin. The scaly patches caused by Psoriasis, called psoriatic plaques, are areas of inflammation and excessive skin production. Skin rapidly accumulates at these sites and takes on a silvery-white appearance. Plaques frequently occur
on the skin of the elbows and knees, but can affect any area including the scalp and genitals. In contrast to eczema, Psoriasis is more likely to be found on the extensor aspect of the joint.

The disorder is a chronic recurring condition that varies in severity from minor localized patches to complete body coverage. Fingernails and toenails are frequently affected (psoriatic nail dystrophy) and can be seen as an isolated finding. Psoriasis can also cause inflammation of the joints, which is known as psoriatic arthritis. Ten to fifteen percent of people with Psoriasis have psoriatic arthritis.

Cause
The exact cause of Psoriasis remains unknown. There may be a combination of risk factors, including genetic predisposition and environmental factors. It is common for Psoriasis to be found in members of the same family. The immune system is thought to play a major role. Despite research over the past 30 years looking at many triggers, the "master switch" that turns on Psoriasis is still a mystery. Factors that may aggravate Psoriasis include stress, withdrawal of systemic corticosteroid, excessive alcohol consumption, and smoking. There are many treatments available, but because of its chronic recurrent nature Psoriasis is a challenge to treat.

The symptoms of Psoriasis can manifest in a variety of forms. Variants include plaque, pustular, guttate and flexural Psoriasis. This section describes each type (with ICD-10 code Psoriasis (''Psoriasis vulgaris'') (L40.0) 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. 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 anybody 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 mildly dry pink skin to big flakes of dry skin that flake off.

Different types of Psoriasis
Psoriasis vulgaris is the medical name for the most common form of Psoriasis ("vulgaris" means common). About 80% of people with Psoriasis have this type. It is also called plaque Psoriasis because of the characteristic plaques on the skin: well-defined patches of red raised skin that can appear on any area of skin, although the knees, elbows, scalp, trunk, and nails are the most common locations. The flaky silvery white buildup on top of the plaques is called scale; it is composed of dead skin cells.

Flexural Psoriasis (inverse Psoriasis) appears as smooth inflamed patches of skin. It occurs in skin folds, particularly around the genitals (between the thigh and groin), the armpits, under an overweight stomach (pannus), and under the breasts (inframammary fold). It is aggravated by friction and sweat, and is vulnerable to fungal infections.

Guttate Psoriasis is characterized by numerous small round spots (differential diagnosis—pityriasis rosea—oval shape lesion). These numerous spots of Psoriasis appear over large areas of the body, such as the trunk, limbs, and scalp. Guttate Psoriasis is associated with streptococcal throat infection.

Pustular Psoriasis Pustular Psoriasis is an uncommon form of Psoriasis. People with pustular Psoriasis have clearly defined, raised bumps on the skin that are filled with pus (pustules). The skin under and around these bumps is reddish. Pustular Psoriasis may cause large portions of your skin to redden. The skin changes that occur before, during, or after an episode of pustular Psoriasis can be similar to those of regular Psoriasis.

Nail Psoriasis produces a variety of changes in the appearance of finger and toe nails. These changes include discolouring under the nail plate, pitting of the nails, lines going across the nails, thickening of the skin under the nail, and the loosening (onycholysis) and crumbling of the nail.

Psoriatic arthritis Psoriatic arthritis is a specific condition in which a person has both Psoriasis and arthritis. Psoriatic arthritis is an autoimmune disease, meaning that the immune system is misdirected to cause inflammation of one's own tissues. Rarely, a person can have psoriatic arthritis without having skin Psoriasis. Moreover, the arthritis can precede the Psoriasis by months or years, or present after years of Psoriasis.

Erythrodermic Psoriasis involves the widespread inflammation and exfoliation of the skin over most of the body surface. It may be accompanied by severe itching, swelling and pain. It is often the result of an exacerbation of unstable plaque Psoriasis, particularly following the abrupt withdrawal of systemic treatment. This form of Psoriasis can be fatal, as the extreme inflammation and exfoliation disrupt the body's ability to regulate temperature and for the skin to perform barrier functions.

A diagnosis of Psoriasis is usually based on the appearance of the skin. There are no special blood tests or diagnostic procedures for Psoriasis. Sometimes a skin biopsy, or scraping, may be needed to rule out other disorders and to confirm the diagnosis. Skin from a biopsy will show clubbed Rete pegs if positive for Psoriasis. Another sign of Psoriasis is that when the plaques are scraped, one can see pinpoint bleeding from the skin below (Auspitz's sign).

Psoriasis is usually graded as mild (affecting less than 3% of the body), moderate (affecting 3-10% of the body) or severe. Several scales exist for measuring the severity of Psoriasis. The degree of severity is generally based on the following factors: the proportion of body surface area affected; disease activity (degree of plaque redness, thickness and scaling); response to previous therapies; and the impact of the disease on the person.

The Psoriasis Area Severity Index (PASI) is the most widely used measurement tool for Psoriasis. PASI combines the assessment of the severity of lesions and the area affected into a single score in the range 0 (no disease) to 72 (maximal disease). Nevertheless, the PASI can be too unwieldy to use outside of trials, which has led to attempts to simplify the index for clinical use.