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A 33-year-old woman presents with uncontrolled psoriasis for 20 years. In addition to the plaque psoriasis (Figure 152-1), she has inverse psoriasis (Figure 152-2). Topical ultrahigh-potency steroids and topical calcipotriol have not controlled her psoriasis. The options for phototherapy and systemic therapy were discussed. The patient chose to try narrowband UVB treatment in addition to her topical therapy.

Figure 152-1

Typical plaque psoriasis on the elbow and arm. (Courtesy of Richard P. Usatine, MD.)

Figure 152-2

Inverse psoriasis in the inframammary folds of the patient in Figure 152-1. This is not a Candida infection. (Courtesy of Richard P. Usatine, MD.)

Psoriasis is a chronic inflammatory papulosquamous and immune-mediated skin disorder. It is also associated with joint and cardiovascular comorbidities. Psoriasis can present in many different patterns from the scalp to the feet and cause psychiatric distress and physical disabilities. It is crucial to be able to identify psoriasis in all its myriad presentations so that patients receive the best possible treatments to improve their quality of life and avoid comorbidities.

Psoriasis affects approximately 2% of the world population.1 The prevalence of psoriasis was 2.5% in white patients and was 1.3% in African American patients in one population study in the United States.2

  • Sex—No gender preference.
  • Age—Psoriasis can begin at any age. In one population study of the age of onset of psoriasis two peaks were revealed, one occurring at the age of 16 years (female) or 22 years (males) and a second peak at the age of 60 years (female) or 57 years (males).3

  • Immune-mediated skin disease, where the T cell plays a pivotal role in the pathogenesis of the disease.
  • Langerhans cell (antigen-presenting cells in the skin) migrate from the skin to regional lymph nodes, where they activate T cells that migrate to the skin and release cytokines.
  • Cytokines are responsible for epidermal and vascular hyperproliferation and proinflammatory effects.

  • Family history.
  • Obesity.
  • Smoking and environmental smoke.
  • Heavy alcohol use.

Table 152-1 lists the factors that trigger or exacerbate psoriasis.4

Table 152-1 Factors that Trigger or Exacerbate Psoriasis

The risk of psoriasis is higher in:5

  • Family history of psoriasis (odds ratio [OR] = 33.96; 95% confidence interval [CI] 14.14 to 81.57)
  • Change in work conditions (OR = 8.34; 95% CI = 1.86 to 37.43)
  • Divorce (OR = 5.69; 95% ...

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