Psoriasis
From Memory Alpha, the free Star Trek reference
Psoriasis is an irritating skin affliction.
In 2376, when Kathryn Janeway asked Tuvok to describe to the con artist Dala the "barbarity" of the Telsian prison system, Tuvok mentioned that torture and disease were commonplace, including "several incurable forms of psoriasis". (VOY: "Live Fast and Prosper")
