Psoriasis

This is why being a hobbit isn't always great.

Definition

A scaly and inflammatory rash caused by hyperproliferation of keratinocytes.

Epidemiology

Affects both sexes pretty much equally and has a prevalence of around 2% in the UK population. There is a genetic element to the disease. It peaks at 15-20 and 55-60 and results in a seronegative arthropathy in about 7% patients.