Board Review: Psoriasis Comorbidities

Overview / Definition Psoriasis is a chronic, immune-mediated inflammatory skin disorder characterized by well-defined erythematous plaques covered with silvery-white scales. It affects approximately 2-3% of the global population and is associated with significant comorbidities that can affect overall health and quality of life. Epidemiology Psoriasis can occur at any age but often manifests in early adulthood, with a peak incidence between ages 15-35 and another peak in middle age. The prevalence of psoriasis varies geographically and is influenced by genetic and environmental factors. Approximately 30% of patients with psoriasis will develop psoriatic arthritis. Psoriasis has a higher prevalence in individuals with a family history of the disease. Comorbidities such as obesity, hypertension, and diabetes are prevalent in psoriasis patients. Pathophysiology / Mechanism The pathogenesis of psoriasis involves a complex interplay of genetic predisposition, immune system activation, and environmental triggers. Key mechanisms include: Immune dysregulation: Increased activity of T-helper 1 (Th1) and Th17 cells leads to the overproduction of pro-inflammatory cytokines (e.g., TNF-alpha, IL-17, IL-23). Keratinocyte hyperproliferation: Cytokines stimulate keratinocyte proliferation, resulting in the characteristic plaques of psoriasis. Angiogenesis: Vascular changes and increased blood flow contribute to the erythema seen in psoriatic lesions. Clinical Presentation Psoriasis presents with distinct clinical features, including: Plaque psoriasis: The most common form, characterized by raised, red lesions covered with silvery scales. Guttate psoriasis: Presents as small, drop-shaped lesions, often following streptococcal infections. Inverse psoriasis: Occurs in skin folds and is often less scaly but more erythematous. Psoriatic arthritis: Joint pain and swelling can occur, affecting up to 30% of patients. Diagnosis / Workup Diagnosis of psoriasis is primarily clinical but may i