Psoriasis is a chronic skin disorder that causes red, scaly patches on the limbs, trunk, scalp, and other parts of the body. It is not contagious.
The rash of psoriasis goes through cycles of improving and worsening. A period of worsening is called a “flare”. At times, psoriasis can be disfiguring, uncomfortable, and even painful.
The scaling and unpleasant appearance of psoriasis lesions (especially if left untreated) can cause embarrassment and be a significant source of anxiety or depression. Psoriasis can also interfere with sleep and make everyday tasks difficult.
Types of Psoriasis
There are five types of psoriasis, each defined by the type of skin lesions that appear.
- 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.
Most people have just one type of psoriasis at a time, but it is possible to have two types simultaneously. And a person with one type of psoriasis (typically plaque psoriasis) may later develop a different type.
Psoriasis can occur anywhere on the body. However, people tend to have areas that are more prone to developing lesions than others. Some places are particularly challenging to treat, including the scalp, face, hands, feet, and nails.
Each psoriasis outbreak can vary in severity. A mild outbreak, with small dandruff-like scales limited to one spot, could be followed by a severe outbreak with large thick plagues covering multiple parts of the body.
There are several ways to measure psoriasis severity.. One simple approach is to measure the amount of the body covered by psoriasis. This is described as the percentage of body surface area.
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. 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.
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. Stay tuned while we will review some of the most common causes of psoriasis next time.
By: Jonathan S. Weiss, M.D.
