ABSTRACT
Psoriasis is one of the many dermatological conditions, including leprosy, which has been described since Biblical times. Robert Willan is considered to have first described psoriasis and identified two varieties of the disease. In 1872, Heinrich Koebner described the induction of lesions of psoriasis within areas of prior trauma in an address delivered to the Silesian Society for National Culture. Coal tar became available with coal gas production in the second half of the nineteenth century and still maintains a role in the treatment of psoriasis. The tumor necrosis factor-alpha (TNF-a) pathway has been an integral pathway targeted by psoriasis, psoriatic and rheumatoid arthritis, and inflammatory bowel disease therapies over the past two decades. Although efalizumab demonstrated efficacy in psoriasis, particularly in those with palmoplantar disease, it was removed from the market in 2009 due to three fatalities from progressive multifocal leukoencephalopathy (PML).
