Dermatology Book

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Dermoscopy

Aka: Dermoscopy, Dermatoscopy, Epiluminescence Microscopy, Incident Light Microscopy, Skin Surface Microscopy
  1. Indications
    1. Risk stratify atypical skin lesions for biopsy
      1. Helps identify Atypical Nevus patterns (reticular, globular, homogenous)
    2. Characterize amelanotic lesions
    3. Distinguish Melanoma and Basal Cell Cancer from benign skin lesions
  2. Preparation: Dermatoscope
    1. Classic or standard dermatoscope
      1. Handheld dermatoscope (10X magnifier) applied over skin with liquid interface (oil, Ultrasound gel or Alcohol)
      2. Better Specificity (due to better characterization of benign structures)
    2. Cross-polarized filtered dermatoscopes
      1. May be used with or without skin contact
      2. Higher sensitivity for skin cancer (due to better vascular appearance)
  3. Technique
    1. Dermatoscope applied to skin (with liquid interface as needed)
    2. Enough pressure applied to eliminate air bubbles
    3. Lesions are evaluated with various pattern recognition protocols
      1. Dermoscopy is complex and only the basic protocol is described here
      2. Graphical, thorough reviews of Dermoscopy are described below
  4. Protocol: Step 1 - Distinguish melanocytic from nonmelanocytic skin lesions
    1. Features present suggestive of melanocytic nevi
      1. Pigment Network
      2. Negative Pigment Network
      3. Aggregated globules
      4. Pseudopods and radial streaming (streaks)
      5. Homogenous blue pigmentation
      6. Pseudonetwork (seen on facial skin)
      7. Parallel pigment pattern (seen on palms and soles)
    2. Distinguish from non-melanocytic lesions (with their own characteristic patterns)
      1. Basal Cell Carcinoma
      2. Seborrheic Keratosis
      3. Hemangioma
      4. Vessels
        1. Non-melanocytic lesion vessels
        2. Melanocytic lesion vessels
      5. Structureless lesions
  5. Protocol: Step 2 - Distinguish Melanoma from benign melanocytic lesions
    1. Method described here uses three point Dermoscopy checklist
      1. Simplest method with highest melanoma Test Sensitivity
    2. Criteria (1 point for each criteria)
      1. Asymmetry in color or structure (not shape or contour asymmetry)
      2. Pigment network is irregular or atypical with thick lines or irregular holes
      3. One or more other atypical features
        1. Blue-white veil
        2. White scar-like depigmentation
        3. Blue pepper-like granules
    3. Interpretation
      1. Biopsy or referral indicated for any lesion with 2-3 criteria present
  6. Resources
    1. Online Dermoscopy tutorial
      1. http://www.dermoscopy.org/atlas/base.htm
    2. Dermoscopy for Family Physician (Am Fam Physician)
      1. http://www.aafp.org/afp/2013/1001/p441.pdf
  7. References
    1. Marghoob (2013) Am Fam Physician 88(7): 441-50 [PubMed]

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