Psoriasis is a complicated disease that is not well understood even though it's been described in medical books for more than 100 years. Part of the reason psoriasis is so complicated is it can show up in many different forms which are described below. You can have just one type of psoriasis or you can have several types of psoriasis -- and what you have now may change completely next year. But your dermatologist must determine which type(s) you have, since medications vary depending on the type of psoriasis.
Plaque Psoriasis
Plaque psoriasis is the most common type of psoriasis. In fact, 90% of all psoriasis is plaque psoriasis. It affects between 0.6 to 4.8% of people in the United States and is slightly more common in men. The plaques tend to get bigger until they reach a certain size, then they may not change for months or years.Scalp Psoriasis
The scalp is the most common place for people with psoriasis to get a rash. Some people might only have a small patch, usually on the back of the head or upper neck, while other people might have a rash that covers their whole scalp.Nail Psoriasis
The nails are often affected by psoriasis. In fact, 80 to 90% of people with psoriasis will have nail changes at some point in their lives. The fingernails are more often affected than the toenails. Psoriasis can affect all aspects of the nail causing various abnormalities.Inverse Psoriasis
Inverse psoriasis is an unusual type of psoriasis that occurs in skin folds. This can make it look like other skin conditions.Guttate Psoriasis
Guttate psoriasis is a common form of psoriasis in children, but it is seen in less than 2% of psoriasis patients. It often occurs 1 to 3 weeks after a viral or bacterial (often streptococcus) respiratory infection.Pustular Psoriasis
Pustular psoriasis (also known as von Zumbusch psoriasis) is a rare, sometimes fatal form of psoriasis.Sources:
Habif, Thomas. "Psoriasis." Clinical Dermatology, 4th Edition. Ed. Thomas Habif, MD. New York: Mosby, 2004. 209-39.
Iizuka, Hajime, et al. "Pathophysiology of generalized pustular psoriasis." Archives of Dermatologic Research 295(2003): s55-9.
Schon, Michael, and W.-Henning Boehncke. "Psoriasis." The New England Journal of Medicine 352(2005): 1899-912.
van de Kerkhof, Peter. "Psoriasis." Dermatology. Ed. Jean Bolognia. New York: Mosby, 2003: 531-5. 125-37
