Psoriasis causes red, scaly patches on the skin.  It is an autoimmune disease and it affects both the skin and the joints.  It is a chronic condition, but it is not contagious.

Psoriasis happens most frequently on the skin of the elbows and knees, but it can appear anywhere.  The red patches that are seen with psoriasis are called psoriatic plaques and they are areas of inflammation caused by increased skin production.  When skin overproduces, it accumulates and takes on a silvery white color.

Psoriasis is considered chronic because it will reappear and may or may not be more severe.  It can also affect the joints and cause an inflammation known as psoriatic arthritis.  It is estimated that ten to fifteen percent of persons with psoriasis have psoriatic arthritis.

It is not known what causes psoriasis.  Some things that may aggravate psoriasis are stress, excessive alcohol consumption and smoking.  There are many treatments available, but psoriasis is a challenge.

Some believe that psoriasis is included in skin conditions written about in the Bible, making it one of the longest known illnesses.  It has been described as a form of leprosy.  The term lepra was used by the Greeks to speak of scaly skin conditions and the term psora was used by them to describe itchy skin conditions.

Psoriasis was given its name in 1841 by a Viennese dermatologist, Ferdinand von Hebra, after years of confusing it with leprosy.

There were many types of psoriasis that were distinguished in the 20th century.  Some of these are:

Plaque psoriasis:  the most common type which affects as much as 90% of people with psoriasis.

Flexural psoriasis:  occurs in skin folds and is aggravated by sweat.

Guttate psoriasis:  a rash appearing type of psoriasis that is associated with strept throat infections.

Pustular psoriasis:  raised bumps filled with pus.

Nail psoriasis:  causes changes in the appearance of both toenails and fingernails.

Psoriatic arthritis:  inflammation of the joints and connective tissue.

Erythrodermic psoriasis:  inflammation of the skin that is widespread, usually the result of poorly managed plaque psoriasis.

Each of these types of psoriasis will be covered in more detail in upcoming posts.