Psoriasis Vulgaris: Pathogenesis, Clinical Features, and Management

Overview / Definition Psoriasis vulgaris is the most common form of psoriasis, affecting approximately 2-3% of the population. It is a chronic, inflammatory skin disease characterized by the presence of well-defined, erythematous plaques covered with silvery-white scales. The condition arises from a combination of genetic, immunological, and environmental factors. Epidemiology Psoriasis vulgaris can occur at any age, but it most commonly presents in young adults, particularly between ages 15-35. Epidemiological studies indicate: Equal prevalence in both sexes, though some studies suggest a slight male predominance. Higher incidence rates in individuals with a family history of psoriasis. Increased prevalence in populations of northern European descent. Pathophysiology / Mechanism The pathogenesis of psoriasis vulgaris involves a complex interplay between the immune system and keratinocytes: Activation of T cells (particularly Th1 and Th17 cells) leads to the production of pro-inflammatory cytokines such as IL-17, IL-22, and TNF-alpha. These cytokines promote hyperproliferation of keratinocytes, leading to the characteristic plaques. Increased angiogenesis and infiltration of immune cells contribute to the inflammatory response. Clinical Presentation Clinically, psoriasis vulgaris is characterized by: Symmetrical, well-demarcated lesions, often located on the elbows, knees, scalp, and lower back. Silvery-white scales that easily shed, revealing a erythematous base. Pruritus and discomfort may accompany the lesions. Additional clinical features may include: Psoriatic arthritis in up to 30% of patients, presenting with joint pain and swelling. Nail changes such as pitting, onycholysis, and discoloration. Diagnosis / Workup The diagnosis of psoriasis vulgaris is primarily clinical, based on the characteristic appearance of the lesions. However, in atypical cases, the following may be employed: Skin biopsy to confirm the diagnosis, which typically shows acanthosis, parak