II. Indications
- Risk stratify atypical skin lesions for biopsy
- Helps identify Atypical Nevus patterns (reticular, globular, homogenous)
- Characterize amelanotic lesions
- Distinguish Melanoma and Basal Cell Cancer from benign skin lesions
III. Preparation: Dermatoscope
- Classic or standard dermatoscope
- Handheld dermatoscope (10X magnifier) applied over skin with liquid interface (oil, Ultrasound gel or Alcohol)
- Better Specificity (due to better characterization of benign structures)
- Cross-polarized filtered dermatoscopes
- May be used with or without skin contact
- Higher sensitivity for Skin Cancer (due to better vascular appearance)
IV. Technique
- Dermatoscope applied to skin (with liquid interface as needed)
- Enough pressure applied to eliminate air bubbles
- Lesions are evaluated with various pattern recognition protocols
- Dermoscopy is complex and only the basic protocol is described here
- Graphical, thorough reviews of Dermoscopy are described below
V. Protocol: Step 1 - Distinguish melanocytic from nonmelanocytic skin lesions
- Features present suggestive of melanocytic nevi
- Pigment Network
- Negative Pigment Network
- Aggregated globules
- Pseudopods and radial streaming (streaks)
- Homogenous blue pigmentation
- Pseudonetwork (seen on facial skin)
- Parallel pigment pattern (seen on palms and soles)
- Distinguish from non-melanocytic lesions (with their own characteristic patterns)
- Basal Cell Carcinoma
- Seborrheic Keratosis
- Hemangioma
- Vessels
- Non-melanocytic lesion vessels
- Melanocytic lesion vessels
- Structureless lesions
VI. Protocol: Step 2 - Distinguish Melanoma from benign melanocytic lesions
- Method described here uses three point Dermoscopy checklist
- Simplest method with highest melanoma Test Sensitivity
- Criteria (1 point for each criteria)
- Asymmetry in color or structure (not shape or contour asymmetry)
- Pigment network is irregular or atypical with thick lines or irregular holes
- One or more other atypical features
- Blue-white veil
- White scar-like depigmentation
- Blue pepper-like granules
- Interpretation
- Biopsy or referral indicated for any lesion with 2-3 criteria present
VII. Efficacy
- Significantly increases melanoma Test Sensitivity (from 76 to 92%) and Test Specificity (from 75 to 95%)
VIII. Resources
- Online Dermoscopy learning resources
- Dermoscopy for Family Physician (Am Fam Physician)