Description

• A chronic, inflammatory disorder commonly characterized by cutaneous erythematous plaques with silvery scale, and varying phenotypes and severity
• Clinical phenotypes:
  • Plaque (vulgaris): ~80% of cases; well-demarcated, red plaques with silvery scale on the scalp, extensor surfaces, and trunk
  • Guttate: <2% of psoriasis patients, usually in patients <30 years of age; abrupt onset of 1- to 10-mm droplet-shaped papules with fine scale on the trunk/extremities, often after strep infection 2 to 3 weeks prior; typically, self-limiting and may resolve spontaneously
  • Inverse: affects intertriginous areas and flexural surfaces; pink-red plaques with minimal scale, without satellite pustules (vs. candidiasis)
  • Erythrodermic: affects ≥90% of body surface area (BSA) with generalized erythema and scaling; associated with desquamation; hair loss; nail dystrophy; and systemic symptoms (chills, malaise, lymphadenopathy, and/or high-output cardiac failure)
  • Pustular: Sterile pustules can present in localized or generalized forms. Generalized pustular psoriasis may lead to severe systemic illness, including superinfection.
  • Nail disease: pitting, oil spots, and onycholysis; nails involved in 50% with psoriasis at diagnosis with lifetime incidence of 80–90% with cutaneous psoriasis; increased association with psoriatic arthritis

Epidemiology

Etiology and Pathophysiology

Psoriasis involves immune dysregulation of dendritic cells, T lymphocytes, and keratinocytes, triggered by infections, stress, and trauma. IL-23 and IL-17 signaling is one of the central signaling pathways in the propagation of psoriasis.

Risk Factors

• Family history
• Obesity
• Local trauma; local irritation (Koebner phenomenon)
• HIV
• Streptococcal infection
• Stress (may contribute to exacerbation)
• Medications: lithium, antimalarials, β-blockers, interferon, TNF-α inhibitors, steroid withdrawal
• Smoking
• Alcohol abuse
• Dysbiosis of gut microbiota

General Prevention

Avoid triggers like trauma, sunburn, smoking, certain medications, alcohol, and stress.

Commonly Associated Conditions

• Psoriatic arthritis
• Seborrheic dermatitis
• Obesity, metabolic syndrome, diabetes, chronic kidney disease
• Cardiovascular disease, atherosclerotic disease
• Nonalcoholic fatty liver disease (NAFLD)
• Other autoimmune conditions: Crohn disease, ulcerative colitis, ankylosing spondylitis
• Psychiatric/psychological conditions: depression, anxiety, suicidal ideation, low self-esteem, alcohol abuse, sexual dysfunction
• Myopathy