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Source: Law RM, Gulliver WP. Psoriasis. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 8th ed. http://accesspharmacy.com/content.aspx?aid=7999031. Accessed June 24, 2012.

  • Chronic inflammatory skin disease characterized by recurrent exacerbations and remissions of thickened, erythematous, and scaling plaques.

  • T lymphocyte–mediated inflammatory disease resulting from genetic predisposition coupled with precipitating factors that trigger abnormal immune response.

  • Receptors on T lymphocytes interact with antigens on surface of antigen-presenting dendritic cells and macrophages.
  • Activated T cells migrate into skin and secrete cytokines (e.g., interferon-γ and interleukin 2 [IL-2]) that induce pathologic skin changes.
  • Genetic component may involve human leukocyte antigens (HLA) Cw6, TNF-α, and IL-3.

  • Affects about 2% of population in United States and Europe.
  • Worldwide prevalence varies between 0.1–3%, with variations due to racial, geographic, and environmental differences.
  • Affects males and females equally; onset usually before age of 40.

  • Factors implicated in development of psoriasis:
    • Skin injury
    • Infection
    • Drugs
    • Smoking
    • Alcohol consumption
    • Obesity
    • Psychogenic stress
  • Therapies that may exacerbate psoriasis:
    • Lithium
    • β-blockers
    • Antimalarials
    • Nonsteroidal anti-inflammatory drugs (NSAIDs)
    • Withdrawal of corticosteroids

Signs and Symptoms

  • Well-demarcated, erythematous, red-violet skin lesions at least 0.5 cm in diameter; typically covered with silver flaking scales.
  • May be single lesions at predisposed areas (e.g., knees and elbows) or generalized over wide body surface area (BSA).
  • Pruritus may be severe and require treatment to minimize excoriations from frequent scratching.
  • Psoriatic arthritis involves both psoriatic lesions and inflammatory, arthritis-like symptoms.
    • Distal interphalangeal joints and adjacent nails most commonly involved, but knees, elbows, wrists, and ankles may also be affected.

Means of Confirmation and Diagnosis

  • Characteristic skin lesions on physical examination
  • Classification as mild, moderate, or severe based on BSA affected and Psoriasis Area and Severity Index (PASI) measurements.

Diagnostic Procedures

  • Skin biopsies not diagnostic of psoriasis.

Differential Diagnosis

  • Minimize or eliminate skin lesions.
  • Alleviate pruritus
  • Reduce frequency of flare-ups.
  • Avoid adverse treatment effects.
  • Provide appropriate counseling (e.g., stress reduction).

  • Figure 1: Treatment algorithm for mild to moderate psoriasis
  • Figure 2: Treatment algorithm for moderate to severe psoriasis

Figure 1.

Treatment algorithm for mild to moderate psoriasis. Reprinted with permission from Wells BG, DiPiro JT, Schwinghammer TL, et al. Pharmacotherapy Handbook. 8th ed. New York: McGraw-Hill, 2012.

Figure 2.

Treatment algorithm for moderate to severe psoriasis. Reprinted with permission from Wells BG, DiPiro JT, Schwinghammer TL, et al. Pharmacotherapy Handbook. 8th ed. New York: McGraw-Hill, 2012.

  • Stress reduction (e.g., guided imagery, stress management)
  • Nonmedicated moisturizers
  • Oatmeal baths
  • Avoidance of harsh soaps and detergents
  • Cleansing with tepid water, preferably with lipid- and fragrance-free cleansers
  • ...

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