Actinic Keratoses

Aka: Actinic Keratoses, Actinic Keratosis

1. See Also
   1. Nonmelanoma Skin Cancer
   2. Squamous Cell Carcinoma
2. Epidemiology
   1. Most common premalignant skin lesion
      1. Responsible for 60% of Squamous Cell Carcinoma involving the skin
   2. Prevalence: White skin (increases with age)
      1. Age 20-29: 10%
      2. Age 80-89: 75%
3. Pathophysiology
   1. Superficial keratotic tumor
   2. Previously considered distinct premalignant changes
   3. Now thought to be very early Squamous Cell Carcinomas
      1. Ortonne (2002) Br J Dermatol 146:20-3
4. Risk Factors
   1. Fair-skinned, blue-eyed persons
   2. Living in sunny climate
   3. Cummulative extensive Sun Exposure
   4. Older persons
5. Symptoms
   1. Typically asymptomatic
   2. May be pruritic or burning
6. Signs
   1. Characteristics: Rough Scaly patches
      1. Discrete, circumscribed
      2. Verrucous or keratotic
      3. White scale or rough patch
      4. Red-brown, pink or skin-colored Macule or Papule
      5. Often recurs after patient "picks off" scale
      6. Vary in size from millimeters to centimeters (typically 2-6 mm in size)
   2. Distribution: Sun exposed areas
      1. Face and neck
         1. Left more common (Car driver's window side)
      2. Dorsal hands
      3. Forearms
7. Diagnosis
   1. Diagnosis by "feel": Rough
   2. Biopsy is rarely indicated
8. Management: Procedures
   1. Cryotherapy with Liquid Nitrogen
      1. Debride hyperkeratotic lesions first
      2. Freeze, slowly thaw and then refreeze
      3. Efficacy increases with duration of freeze time
         1. Freeze 5 seconds: 39% cure rate
         2. Freeze 20 seconds: 83% cure rate
   2. Curettage
      1. Infiltrate area with local anesthetic
      2. Consider for hyperkeratotic lesions
      3. Adjuncts
         1. Trichloroacetic acid (TCA) before curettage
         2. Electrosurgery post-curettage to destroy residual tissue
   3. Photodynamic therapy
      1. Photosensitizer applied to skin followed by exposure to specific light source
      2. Protocols
         1. Aminolevulinic Acid (Levulan Kerastick): Exposure to blue light after 14 hours
         2. Methyl aminolevulinate (Metvixia): Exposure to red light after 3 hours
9. Management: Topical Treatments with Keratolytics
   1. Indicated when >15 lesions present
   2. Topical 5-Flourouracil
      1. Preparations
         1. Fluorouracil cream 5% (Efudex)
         2. Fluorouracil cream 1% (Fluoroplex)
         3. Fluorouracil microspore cream 0.5% (Carac)
      2. Adverse effects
         1. Dryness, erythema, irritation and even disfigurement on the face
         2. More common with 5% cream; 0.5% appears better tolerated
      3. Technique
         1. Use bid for 2-4 weeks until marked inflammation
         2. Consider 0.5% cream for one week prior to Cryotherapy
   3. Topical Diclofenac 3% gel in 2.5% hyaluronic acid (Solaraze)
      1. Technique: Apply twice daily for 90 days
      2. Efficacy
         1. Complete resolution in 50% of cases
         2. Less effective than Imiquimod (Aldara), 5-Fluorouracil (5-FU) or ingenol (Picato)
      3. Adverse Effects
         1. Skin inflammation (Local irritation, dryness and Pruritus_
            1. Less irritating than Imiquimod (Aldara), 5-Fluorouracil (5-FU) or ingenol (Picato)
      4. Reference
         1. Rivers (1997) Arch Dermatol 133:1239-42
   4. Imiquimod 5% Cream (Aldara)
      1. Applied 3-4 times weekly at bedtime and wash off in AM; use for up to 16 weeks
      2. Efficacy
         1. Complete response in up to 57% of patients
         2. Partial response (75% reduction) in up to 72% of patients
      3. Adverse effects
         1. Cosmetic outcomes not studied
         2. Severe erythema (80%)
         3. Severe Erosions (40%)
      4. References
         1. Stockfleth (2002) Arch Dermatol 138:1498-502
   5. Ingenol mebutate (Picato gel)
      1. Technique: Total course is 2-3 days
         1. Picato 0.05%: Apply to torso or extremities for 2 days
         2. Picato 0.015%: Apply to face or scalp for 3 days
      2. Adverse effects
         1. Skin irritation (erythema, flaking or crusting)
      3. Efficacy
         1. Similar to Imiquimod and 5-Fluorouracil
   6. Chemical Peels for face (applied by dermatology)
      1. Similar efficacy to fluorouracil
      2. Preparations
         1. Jessner's Solution (Resorcinol, Lactic Acid, Salicylic acid)
         2. Trichloroacetic acid 35% (Tri-Chlor)
      3. References
         1. Lawrence (1995) Arch Dermatol 131:176-81
10. Prevention
    1. See Sun Exposure (lists general preventive measures)
    2. See Sunscreen
11. Course
    1. Spontaneous resolution in 25% of lesions over 12 months
    2. Progression to squamous cell cancer: 6-10% over 10 years
    3. Higher risk of Squamous Cell Carcinoma progression in thick tumors (especially on scalp)
12. References
    1. Habif (2004) Dermatology p. 736-43
    2. Mcintyre (2007) Am Fam Physician 76(5):667-71
    3. Stulberg (2004) Am Fam Physician 70:1481-8