Fitzpatrick’s Color Atlas and Synopsis of Clinical Dermatology, 9e

Appendix B: Dermoscopy

Nicole Trepanowski; Rebecca I. Hartman

INTRODUCTION

Dermoscopy uses a device (i.e., dermatoscope) that magnifies and polarizes light to view the skin in more detail. Photography can be used with dermoscopy to monitor skin lesions over time. Dermoscopy significantly improves the sensitivity and specificity of melanoma detection, but also has a role in nonmelanoma skin cancer detection and in inflammatory dermatoses. Epiluminescence microscopy, incident light microscopy, skin-surface microscopy, and dermatoscopy are synonyms.

Uses

Different types of light: polarized or nonpolarized.
Polarized dermoscopy can be contact or noncontact, whereas nonpolarized dermoscopy is contact only.
Contact requires an interface such as alcohol, gel, or oil, whereas noncontact does not.

Nonpolarized light highlights specific features, such as blue-gray veil, peppering, milia-like cysts, and comedo-like openings. Polarized contact dermoscopy is particularly useful for visualizing melanin pigment and shiny-white streaks. On the other hand, polarized noncontact dermoscopy is useful for examining blood vessels and red or pink pigment.

Features of melanocytic lesions include pigment network, aggregated globules, radial streaming or pseudopods, and homogeneous blue pigment (Table B-1) (Figures B-1, B-2, B-3). Of note, pigmented lesions on special sites have unique patterns including the parallel furrow pattern on acral surfaces and the pseudo-network on the face. The second step involves determining whether the lesion is benign or malignant. For melanocytic lesions in general, malignant lesions tend to display disorder, chaos, asymmetry, and often have an abnormal variant of a benign pattern. Melanoma-specific features include atypical network, negative network, atypical streaks, blotch, atypical dots or globules, regression, blue-gray veil, atypical vasculature structures, and crystalline structures (Figures B-4 and B-5). If there is high suspicion for melanoma, the lesion should be biopsied. If the lesion is indeterminate, the lesion should be biopsied or if flat, may be monitored, depending on the level of suspicion and the clinical scenario.

TABLE B-1Dermoscopic Features of Benign and Malignant Melanocytic Lesions

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TABLE B-1 Dermoscopic Features of Benign and Malignant Melanocytic Lesions

Melanocytic Lesions

Dermoscopic Features

Benign

Blue nevus

Homogeneous blue pigmentation

Nevus

Regular, symmetric network. Network may be diffuse reticular, patchy reticular, peripheral network with central hypo- or hyperpigmentation, or peripheral network and central globules. Additional patterns include globular, globular cobblestone, reticular peripheral globular, homogeneous brown, homogeneous blue, two components, structureless tan/pink, multicomponent (symmetric), tiered globular, or starburst.

Malignant

Melanoma

Atypical or negative pigment network. Can have atypical streaks (pseudopods and radial streaming), off-centered blotch, atypical dots or globules, regression, blue-gray veil, atypical vasculature, crystalline structures, or peripheral tan-brown structureless areas. Patterns are often disorganized and asymmetric.