H13 Leprosy and psoriasis: a heated controversy

Abstract

Abstract In the Old Testament, the term ‘Lepra’ was used to describe many skin diseases, including psoriasis, eczema, vitiligo, alopecia areata and boils. The word ‘leprosy’ was derived from this and was previously used as a generic term that included multiple inflammatory dermatological diseases. It was a disorder of great religious significance during ancient times, with intense stigmatization—‘lepers’ were pronounced unclean by priests. Hippocrates (460–377 Bc), the Greek ‘father of medicine’, can be credited with being the first to separate medicine from religious superstition. However, there was little differentiation between leprosy and psoriasis, two distinct diseases we know today. He used the word ‘psora’ to describe itch, and ‘lopoi’ to describe the dry and scaly features of skin conditions, thus continuing the confusion between leprosy and psoriasis. The failure to differentiate psoriasis as its own clinical entity from leprosy meant that for many centuries, patients with psoriasis also suffered the same cruel fate as those with leprosy in society. Those suffering from leprosy were wrongly believed to be highly contagious and were forced to carry a bell or clapper to announce their approach to those who were considered healthy. They were required to wear distinctive clothing so that they were easy to recognize by the public, and were not permitted to talk to or even touch a healthy person. They were outcast in society and could only mix with other ‘lepers’. In 1313, Philip the Fair of France horrifically ordered all those outcasts to be burned at the stake. In 1809, Robert Willan (1757–1812), an English doctor, marvellously developed a simple classification of skin diseases that offered a clear description of the different types of psoriasis. This was a crucial milestone in the recognition of psoriasis as a separate skin disease from leprosy. However, while he was the first person to describe psoriasis as a separate condition, he failed to eliminate leprosy completely as an associated disease. He used the term ‘lepra vulgaris’ to discuss modern psoriasis, which once again further perpetuated the confusion between psoriasis and leprosy. Ultimately, it was Ferdinand von Hebra (1816–1880), an Austrian physician, who permanently shed the term ‘lepra’ from the description of psoriasis in the 1800s, finally allowing the two diseases to be separate.