Psoriasis--100 years ago.

Psoriasis appears to be a very old disease. Notwithstanding that, it has been described as a clinical entity only in the early 19th century. By the end of that century, psoriasis comprised a spectrum of clinical variants which have remained almost unchanged since. And despite a wealth of new information on this disease, both etiology and pathogenesis are still elusive and a matter of discussion and controversy in our days. A perspective as to the state of the art 100 years ago is presented.