Psoriasis is probably one of the longest known illnesses of humans and simultaneously one of the most misjudged and misunderstood. Some scholars believe psoriasis to have been included among the skin conditions called tzaraat in the Bible.
Tzaraat was a punishment for sin whose cure could only be found in repentance and forgiveness. In more recent times psoriasis was frequently described as a variety of leprosy. It became known as Willan's lepra in the late 18th century when English dermatologists Robert Willan and Thomas Bateman differentiated it from other skin diseases and provided the first rational nomenclature based on the appearance of lesions. Willan identified two categories: leprosa graecorum and psora leprosa.
While it may have been visually, and later semantically, confused with leprosy it was not until 1841 that the condition was finally given the name psoriasis by the Viennese dermatologist Ferdinand von Hebra. The name is derived from the Greek word psora which means to itch.[3]
It was during the 20th century that psoriasis was further differentiated into specific types.
