Psoriasis
Overview
Plain-Language Overview
Psoriasis is a chronic skin condition that primarily affects the skin and joints. It causes the skin to develop red, scaly patches that can be itchy and sometimes painful. This happens because the body's immune system mistakenly speeds up the growth cycle of skin cells. The condition can affect any part of the body but is most common on the elbows, knees, scalp, and lower back. Psoriasis can also impact a person's quality of life due to its visible symptoms and potential joint pain. It is not contagious and often follows a pattern of flare-ups and remissions. Managing inflammation is key to controlling symptoms.
Clinical Definition
Psoriasis is a chronic, immune-mediated inflammatory disease characterized by hyperproliferation of keratinocytes and inflammatory infiltration in the skin. It is primarily driven by dysregulation of the IL-23/Th17 axis, leading to increased production of proinflammatory cytokines such as IL-17 and TNF-alpha. The hallmark clinical presentation includes well-demarcated, erythematous plaques with silvery scales, commonly on extensor surfaces. Genetic predisposition involves multiple loci including HLA-C and IL12B. The disease can also manifest as psoriatic arthritis, affecting joints and entheses. Chronic inflammation in psoriasis increases the risk of comorbidities such as cardiovascular disease and metabolic syndrome. Diagnosis is clinical but may be supported by histopathology showing acanthosis, parakeratosis, and Munro microabscesses.