Solar Lentigo

1. Epidemiology
   1. Onset over age 30-40 years
   2. Most common in Caucasian skin (also seen in Asians)
2. Pathophysiology
   1. Proliferation of basal Melanocytes, increasing melanization
   2. Contrast with Freckles which are a result of increased Melanin production
3. Signs
   1. Characteristics
      1. Small Macules 1-3 cm (up to 5cm)
      2. Light yellow to light ot dark brown in color
      3. Round or oval with slightly irregular border
   2. Distribution: Chronically sun exposed areas
      1. Forehead
      2. Cheeks
      3. Nose
      4. Hand and Forearm dorsum
      5. Upper back
      6. Chest
      7. Shins
4. Differential Diagnosis
   1. Hyperkeratotic lesions (distinguish from the smooth flat surface of Lentigo)
      1. Flat Seborrheic Keratosis
      2. Pigmented Actinic Keratosis
   2. Lentigo maligna (biopsy if suspected)
   3. Freckle
   4. Syndrome with multiple Lentigines
      1. Peutz-Jeghers Syndrome
      2. LEOPARD Syndrome
      3. LAMB Syndrome
5. Red Flags (suggesting biopsy)
   1. Rapid growth
   2. Lesions suspicious for Melanoma
   3. Symptomatic lesions
      1. Pain
      2. Recurrent bleeding
      3. Poor healing
6. Management
   1. Light Cryotherapy (<10 seconds) with Liquid Nitrogen
      1. Lesion will disappear for 1 to 3 years
   2. Chemical Peel
      1. Trichloroacetic acid (Trichlor) 30-35%
   3. Laser therapy (ND:YAG Laser)
   4. Bleaching with Hydroquinone (Eldoquin Forte) 3-4%
      1. May result in blotchy Hyperpigmentation (ochronosis) and may take months to see result
   5. Mequinol 2%/Tretinoin 0.01% (Solage) topical solution
   6. Tazarotene (Tazorac) 0.1% cream
   7. Adapalene (Differin) 0.1-0.3% gel
7. References
   1. Plensdorf (2009) Am Fam Physician 79(2): 109-16