Psoriasis is a autoimmune, chronic, inflammatory and proliferative skin disorder. The lesions consist of red, scaly, sharply demarcated, indurated plaques, present particularly over the extensor surfaces and scalp. Psoriasis can be of plaque, inverse, guttate, erythrodermic, pustular types. Plaque psoriasis is the most common form, affecting approximately 80% to 90% of patients. Plaque psoriasis manifests as well-defined, sharply demarcated, erythematous plaque varying in size from 1 cm to several centimeters. Psoriatic plaques typically have a dry, thin, silvery-white or micaceous scale.
