LEP and psoriasis: While studies showed that the serum leptin levels were elevated in psoriatic patients with normal body mass index (BMI) and correlated with the psoriasis area and severity index (PASI) scores [143,144,145]—suggesting that the increased leptin concentrations in the serum might not only be derived from adipocytes but also from dermal cells—another study did not find a relationship between the circulating leptin concentrations and the PASI score [146].