Types of Psoriasis
Various forms of psoriasis exist. Some can occur alone or at the same time as other types, or one may follow another. The most common type is called plaque psoriasis, also known as psoriasis vulgaris.
Plaque psoriasis leads to skin patches that start off in small areas, about 1/8 of an inch wide. They usually appear in the same areas on opposite sides of the body.
The patches slowly grow larger and develop thick, dry plaque. If the plaque is scratched or scraped, bleeding spots the sizes of pinheads appear underneath. This is known as the Auspitz sign.
Some patches may become ring-shaped (annular), with a clear center and scaly raised borders that may appear wavy and snake-like.
As the disease progresses, eventually separate patches may join together to form larger areas. In some cases, the patches can become very large and cover wide areas of the back or chest. These are known as geographic plaques because the skin lesions resemble maps.
Plaque psoriasis may persist for long periods of time. More often it flares up periodically, triggered by certain factors such as cold weather, infection, or stress.
Patches most often occur on the:
- Lower back
They may also be seen on the:
Review Date: 10/21/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.