Exploring different Theories.

The 1800's were filled with different observations and theories by a variety of doctors.

One in particular shared his observations, which are still considered valid today, with the rest of the scientific world.

In 1872, Heinrich Koebner delivered a lecture that described how one of his patients experienced a severe outbreak of Psoriasis in specific areas of skin that had been damaged by a horsefly bite, a recent tattoo and an area of skin where it had been rubbed raw from horseback riding.

Koebner believed that there is a peculiar disposition in the skin of those with Psoriasis that remains dormant for years. This predisposition produces an inflammation of the skin, when stimulated by any internal or external stimuli.

In the case of Koebner's patient, it was the combination of the riding sores, horse-fly bite and tattoo that resulted in Psoriasis. Koebner thought that the Psoriasis was caused by something that happened internally, but modern day researchers have found that the skin must be damaged or aggravated in some way in order to produce the Koebner reaction.

Investigators are intrigued by the Koebner phenomenon because it is the only known way Psoriasis can be induced. And since there is no animal model to study, cases of the Koebner phenomenon are very important to the scientific world.

Other theories that were explored in the late 1800's and early 1900's were the influence of infections on Psoriasis. Infections were very common in young people in the first part of the 20th century which usually resulted in guttate Psoriasis.

Studies done a few years later in the 1930's showed that patients mentioned having tonsillitis before their first attack of Psoriasis. In 1947, another report showed that 54% of 66 patients with Psoriasis had a positive test for streptococcal agglutination, a mass of infectious cells that cause throat infections and may precipitate many diseases in genetically predisposed individuals.