When it comes to psoriasis—don’t judge the skin by its cover. Psoriasis may look like a cosmetic problem, but it’s much, much more than that. (Learn about other common psoriasis myths here.)
Psoriasis is an autoimmune disease, and the most prevalent one in the United States at that. Of the 7.5 million Americans who suffer from psoriasis—approximately 2.2 percent of the population—about 60 percent report that the condition significantly affects their quality of life.
Psoriasis is a chronic condition that develops when a person’s skin cells grow too quickly (forming in a few days rather than weeks) due to faulty signals from the immune system. The body doesn’t shed these cells, so they pile up on the surface of the skin, which causes patches of psoriasis to appear. Learn more about psoriasis and its symptoms here.
The symptoms of psoriasis depend on the type of psoriasis you have. “Psoriasis doesn’t have a classic presentation in every patient,” says Suzanne Friedler, MD, a dermatologist in New York City. “That’s why if you have a rash that’s difficult to identify, you should see your dermatologist.”
Understanding the Psoriasis Types
There are five different types of psoriasis: plaque, guttate, inverse, pustular, and erythrodermic. These different types can appear alone, or with another type.
1. Plaque psoriasis is the most common form. “It appears with red, well-defined plaques that may be present on the elbows, knees, lower back and scalp,” says Friedler. The plaques are often raised, red patches covered with a silvery white buildup of dead skin cells. They’re often itchy and painful, and they can crack and bleed.
2. Guttate psoriasis is the second most common form of psoriasis. About 10 percent of people who get psoriasis develop guttate psoriasis. “Guttate psoriasis can look like little red dots scattered all over your body, and some of them will have scales on them,” says Friedler.
Guttate psoriasis often starts in childhood or young adulthood, and may be triggered by a strep infection. “Because guttate psoriasis is often preceded by a strep infection, it is highly responsive to antibiotics,” says Friedler.
3. Inverse psoriasis is different from other types of psoriasis in that it doesn’t present with a thick, white scale. Inverse psoriasis shows as red lesions that are sometimes smooth and shiny. They often show up in body folds, like behind the knee, under the arm, or in the groin. “Psoriasis in these areas are often mistaken as a fungal infection or some other condition,” says Friedler.
4. Pustular psoriasis is when a person has white pustules (blisters of non-infectious pus that contain white blood cells) surrounded by red skin. “[Pustular psoriasis] can appear anywhere on the body, but it’s most common on the palms and soles [of the feet],” says Friedler.
5. Erythrodermic psoriasis is rare, but it’s also the most severe form of psoriasis. It causes widespread, fiery redness that covers most of the body. It’s itchy, painful and can cause the skin to come off in sheets.
Erythrodermic psoriasis occurs in about 3 percent of people who’ve had psoriasis during their lifetime. “It can be life-threatening, so if you have this type of psoriasis you should seek medical attention immediately,” says Friedler.
“Psoriasis can look different from patient to patient, and even in the same patient in the course of their lifetime,” says Frielder. “If you have a new rash, or a rash that’s changing, it might be psoriasis. Speak to your dermatologist to get the best answer.”