Psoriasis

Psoriasis is a chronic skin condition that causes red, scaly patches that result from the overgrowth of skin cells. Psoriasis is not contagious.

Psoriasis symptoms may come and go through cycles (“flares”). During a psoriasis flare, the skin develops unsightly skin lesion that be painful and lead to embarrassment, creating a significant source of anxiety or depression. Psoriasis can also interfere with sleep and make everyday tasks difficult.

There are five types of psoriasis, each defined by the type of skin lesion.

• Plaque psoriasis appears as thickened, red scaly lesions called plaques. This is the most common type of psoriasis.
• Guttate psoriasis appears as small, drop-shaped spots on the trunk, limbs, and scalp. This is often triggered by bacterial infections, such as strep throat.
• Inverse psoriasis appears as smooth, red patches in the folds of skin near the genitals, breasts, or armpits.
• Erythrodermic psoriasis appears as a scaly, red, peeling rash that afflicts the entire body. This is an uncommon form.
• Pustular psoriasis appears as pus-filled blisters that can be widespread or localized to the hands or feet. Also uncommon.

The same person may develop different types of psoriasis at different times and each psoriasis flare can vary in its severity.

About 10-30% of people with psoriasis will also develop psoriatic arthritis. Symptoms of psoriatic arthritis include stiffness, pain, and swelling of the tendons and joints, as well as morning stiffness and generalized fatigue.

Psoriasis Severity

There are several ways to measure psoriasis severity.

One way to gauge psoriasis severity is to measure the body area covered by psoriasis. This is described as the percentage of body surface area (BSA). The area beneath one hand, including fingers and thumb, is equal to 1% of your BSA. If the skin affected by psoriasis is roughly equal to the area beneath 2 hands, then about 2 percent of the body is affected.

• Mild psoriasis affects less than 3% of the body.
• Moderate psoriasis affects 3 to 10% of the body.
• Severe psoriasis affects more than 10% of the body.

Of those with psoriasis, 65% of people have mild psoriasis, 25% have moderate psoriasis, and 8% have several psoriasis.

However, this approach does not capture other important factors. Psoriasis severity is also influenced by the type of psoriasis, the impact the illness has on a person’s quality of life, and a person’s susceptibility to side effects from treatment. For instance, psoriasis is generally considered severe if it covers the palms and soles because of its impact on a person’s ability to walk and perform day-to-day tasks.

Medical researchers that perform clinical studies of psoriasis use a severity measurement called the Psoriasis Area Severity Index (PASI). This is a widely used standard that may appear in medical literature or on information about psoriasis medications, but is too complex for routine use in the clinic.