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Psoriasis

•  prevalence estimated at 1-3% of the population
•  positive family history in 30% of patients; inheritance is "multifactorial"
•  can develop any time during life

Pathogenesis

•  basic defect in psoriasis is unknown
•  psoriasis is a chronic immunologic disease of the skin characterized by profound
   cutaneous inflammation and epidermal hyperproliferation
•  in psoriasis, it takes 3-4 days for a keratinocyte to transit from the basal layer to the
   surface where it is shed; this process takes 28 days in normal skin
•  one of the current leading theories is that the epidermal hyperproliferation is secondary
   to the cutaneous inflammation
•  key role for T
h1 cells (type 1 T helper cells which produce interferon-g and IL-2)
•  psoriasis is known to be aggravated by environmental factors:
                     - Koebner phenomenon
                     - infections:
                                - group A streptococcal infections can precipitate acute guttate
                                   psoriasis
                                - psoriasis may be precipitated or worsened by HIV infection
                     - stress: can be difficult to distinguish between stress that worsens
                                  psoriasis from psoriasis that causes stress
                     - alcohol and drugs:
                                - prednisone: can cause severe flare up of psoriasis after
                                 discontinuation
                                - beta blockers, lithium (plus many others)
                                - any cutaneous drug eruption can Koebnerize psoriasis

     Psoriasis

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     Psoriasis

     Show me where and show me details


     Psoriasis
      - Clinical:
          - key features
          - sites of predilection
          - variants of psoriasis
                 - guttate psoriasis
                 - inverse psoriasis
                 - pustular psoriasis
                 - erythrodermic psoriasis
      - Pathogenesis:

          - koebner phenomenon
      - Complications
      - Treatment
      - Micropathology 

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