It was Dr. Ferdinand Ritter Von Hebra who first used the term psoriasis in 1841 to describe this disease. Von Hebra was a dermatologist at the University of Vienna. He was the first doctor to study skin diseases from the viewpoint of anatomical pathology. In other words, he studied various skin diseases under the microscope and categorized them according to their microscopic features. This meticulous approach cleared up much confusion about the causes and nature of various skin diseases, many of which looked similar to the naked eye. Von Hebra's work remains a foundation upon which we continue our understanding of skin diseases. Of course, we now have new tools at our disposal -- including molecular and genetic studies -- which he could only dream of.
The term psoro comes from the Greek word for itch; psoriasis corresponds with the term itchy. The term psoriasis was used as early as 1684 as the Latin term for mange. Mange is simply another word for scabies, a very itchy mite infestation (which, in fact, has no relation to psoriasis).
Von Hebra used the term psoriasis to describe the disease we all know today as psoriasis. Once his system of skin classifications became the standard, all other names for this disease were relegated to historical status.