Psoriasis: Overview and Diagnosis

Psoriasis is a chronic, common, inflammatory skin disease. The classic skin lesions can be described as sharply demarcated, scaly, erythematous plaques often found on the extensor surfaces. Several variants of psoriasis have also been described, including palmoplantar, pustular, erythrodermic, and guttate forms. Although psoriasis is usually diagnosed clinically, characteristic histologic findings include hyperkeratosis, parakeratosis, and acanthosis of the epidermis with dilated blood vessels and a lymphocytic infiltrate. Psoriasis is an immune-mediated disease, and although the etiology is not fully understood, genetic and environmental factors have been implicated. Importantly, psoriasis is associated with a number of systemic complications and comorbidities that have a high impact on affected patients.