Epidemiology, clinical manifestations, and diagnosis

Overview

Psoriasis is a common chronic inflammatory skin disease that has also been identified as a multisystem inflammatory disorder associated with multiple comorbidities.

Epidemiology

Psoriasis affects males and females equally. Psoriasis can begin at any age; however, onset during adulthood is most frequent. 

Pathophysiology

Psoriasis is a complex immune-mediated disease. Genetic factors play an important role, and multiple genes have been associated with susceptibility to psoriasis. The psoriasis-susceptibility (PSORS1) locus within the major histocompatibility complex (MHC) on chromosome 6p21 is considered a major genetic determinant of this disease. 

Clinical manifestations

There are multiple clinical subtypes of psoriasis. Chronic plaque psoriasis, the most common form of psoriasis, most often presents with sharply defined, erythematous plaques with overlying, coarse scale. The scalp, extensor elbows, knees, and gluteal cleft are common locations for chronic plaque psoriasis. Other major subtypes include guttate psoriasis, pustular psoriasis, and erythrodermic psoriasis. 

Associated disorders

Individuals with psoriasis are at risk for psoriatic arthritis and multiple other comorbidities. Examples of other comorbidities linked to psoriasis include obesity, metabolic syndrome, hypertension, diabetes, and atherosclerotic disease. 

Diagnosis  

A diagnosis of psoriasis can be made by physical examination in the vast majority of patients. Occasionally, a skin biopsy is needed to rule out other conditions.