Psoriasis is a common skin disease which presents as red, scaley lesions known as plaques. Recent experiments have shown that within these plaques, the signalling molecule nitric oxide is actively produced. I will present a mathematical model that investigates the dynamics of nitric oxide within psoriatic plaques. Using the model, I will suggest an explanation for the observed nonlinear relationship between nitric oxide release rates and plaque erythema (redness). I will go on to investigate the possibility that the high nitric oxide levels within psoriatic plaques may regulate the formation of extended rete pegs, which are a hallmark of the disease.