Psoriasis

Aka: Psoriasis, Chronic Plaque Psoriasis, Guttate Psoriasis

1. Epidemiology
   1. Onset in young adulthood between ages 30 to 40 years
   2. Prevalence: 1-2% of general population
   3. Men and women affected equally
2. Pathophysiology
   1. Autoimmune
      1. Viral infection may precipitate process
      2. T-Cell-mediated autoimmune response
         1. Cytokines released and stimulate Keratinocytes
   2. Keratinocytes proliferate
      1. Epidermal cells proliferate too fast
         1. Cells cycle in 4 days instead of normal 3-4 weeks
      2. Abnormal keratin production
      3. Dermal inflammation
3. Associated environmental factors
   1. Suppressed by:
      1. Sun and humidity
   2. Provocative
      1. Injury to skin (Koebner Reaction)
      2. Streptococcal Pharyngitis
      3. Emotional upset
      4. HIV Infection (severe exacerbations)
      5. Medications
         1. Antimalarials
         2. Beta Blockers
         3. Lithium
         4. NSAIDS
4. Symptoms
   1. Pruritus is present in >80% of psorisis
      1. Psora is greek for itching
5. Signs: Chronic Plaque Psoriasis
   1. Description
      1. Widespread
      2. Sharply demarcated
      3. Bright pink Plaques
      4. Overlying loose, silvery scale
   2. Location: Symmetrical
      1. Over joints and extensor surfaces of extremities
      2. On trunk, especially lower back and buttocks
      3. Palms and soles
      4. Scalp
      5. Umbilicus
   3. Signs suggestive of Psoriasis
      1. Auspitz Sign
      2. Koebner Phenomenon
6. Signs: Associated findings
   1. Location specific signs
      1. Nail
         1. Nail Pitting
         2. Onycholysis
            1. Separation of distal edge of nail from nail bed
            2. Accumulation of crumbly subungual debris
      2. Gluteal cleft
         1. Eroded pinkness in crease
      3. Penis
         1. Pink Macules or Plaques on penis
      4. Large joints
         1. Hyperkeratosis over elbows, knees, and ankles
      5. Tongue
         1. Geographic Tongue (rare)
   2. Uncommon Clinical Variants
      1. Guttate (drop-like)
      2. Inverse (flexural)
      3. Pustular
      4. Erythroderma
   3. Systemic Signs
      1. Psoriatic Arthritis
      2. Uveitis (up to 20% of Psoriatic Arthritis cases)
   4. Severe widespread Psoriasis systemic signs
      1. Benign Lymphadenopathy
      2. Fever, chills, and Hyperthermia
      3. Increased cardiac demand
      4. High output Heart Failure
      5. Increased Sedimentation Rate and Uric Acid
      6. Decreased Serum Albumin
      7. Iron Deficiency Anemia
7. Differential diagnosis
   1. Lichen Simplex Chronicus
   2. Nummular Eczema
   3. Seborrheic Dermatitis
   4. Tinea Corporis
   5. Group A Beta Hemolytic Streptococcus
      1. May present as Guttate Psoriasis in children
      2. Obtain ASO Titer and Throat Culture
8. Associated Conditions (related to psoriatic medications)
   1. Non-Melanoma skin cancer
   2. Lymphoma
9. Approach: Moderate Chronic Plaque Psoriasis
   1. Trunk and extensor surface involvement
      1. Initial and exacerbation therapy (<4 weeks only)
         1. Protocol 1: Steroid and Calcipotriene
            1. High potency Topical Corticosteroid qAM
            2. Calcipotriene applied qPM
         2. Protocol 2: Single agent
            1. High potency Topical Corticosteroid or
            2. Calcipotriene or
            3. Tazorotene (Tazorac)
      2. Long-term maintenance (beyond 4 weeks)
         1. Calcipotriene or
         2. Tazorotene (Tazorac)
   2. Flexor surface involvement
      1. Moderate Topical Corticosteroids (<4 weeks) or
      2. Tacrolimus or Pimecrolimus
   3. Scalp involvement
      1. Exacerbations
         1. Topical Corticosteroid (brief use)
         2. Example: Clobetasol 0.05% Shampoo
      2. Maintenance
         1. Anti-DandruffShampoo
         2. Examples: T-gel or selsun
   4. Adjuncts
      1. Lac-Hydrin or salicylic acid applied daily
10. Approach: Severe Chronic Plaque Psoriasis
    1. Criteria
       1. Psoriasis refractory to above therapy
       2. Chronic Plaque Psoriasis involving >20% of body
    2. Protocol usually managed by dermatology
       1. Use above topical agents
       2. See Ultraviolet light below
       3. See Systemic Agents below
11. Management: Topical Preparations
    1. Topical Corticosteroids
       1. High Potency Topical Steroids (Usually indicated)
          1. Very high potency: e.g. Clobetasol (Temovate)
          2. High potency: e.g. Fluocinonide (Lidex)
       2. Low Potency Topical Steroids
          1. Face
          2. Genitals
          3. Maintenance Therapy
    2. Vitamin D based topicals
       1. Calcipotriene (Dovonex)
       2. Used in combination with Topical Corticosteroids
    3. Retinoid based topicals
       1. Tazarotene (Tazorac)
       2. More irritating than Calcipotriene
    4. Immunosuppressant based topicals
       1. Tacrolimus 0.1% or Pimecrolimus 0.1% creams
          1. Effective in facial and intertriginous Psoriasis
          2. Lebwohl (2004) J Am Acad Dermatol 51:723-30
    5. Adjunctive agents in combination with above
       1. Topical Salicylic Acid (Keratolytic Agent)
    6. Poorly tolerated topicals (use Calcipotriene instead)
       1. Historically used with UVB light exposure
       2. Anthralin (Anthra-Derm)
       3. Coal Tar (e.g. Zetar)
12. Management: Ultraviolet Light
    1. Risk of non-Melanoma skin cancer
    2. Protocols
       1. Ultraviolet B exposure alone
       2. Ultraviolet A exposure with psoralen (PUVA)
          1. Increased risk of non-Melanoma skin cancer
13. Management: Systemic agents (most are higher risk)
    1. Immunosuppressants
       1. Etretinate
       2. Cyclosporine
       3. Methotrexate (unclear efficacy)
    2. Biologic agents (Cost from $10k to >$20k/year)
       1. Tumor necrosis factor (tnf) receptor blockers
          1. Etanercept (Enbrel)
             1. Leonardi (2003) N Engl J Med 349:2014-22
          2. Infliximab (Remicade)
             1. Winterfield (2004) Dermatol Clin 22:437-47
       2. Other mechanisms
          1. Alefacept (Amevive)
          2. Efalizumab (Raptiva)
             1. Lebwohl (2003) N Engl J Med 349:2004-13
    3. Thiazolidinedione (Avandia, Actos) - experimental
       1. Appears effective in Psoriasis even in non-diabetics
       2. Only small trials support to date
       3. Ellis (2000) Arch Dermatol 136(5):609-16
14. References
    1. Luba (2006) Am Fam Physician 73:636-46
    2. Mason (2002) Br J Dermatol 146:351-64