Pattern analysis

Learning objectives
Introduction
Benign melanocytic lesions
Melanoma
Activity

Learning objectives

• Describe dermoscopic diagnosis of melanocytic lesions using pattern analysis

Introduction

In dermoscopy, the first step algorithm identifies whether a lesion is melanocytic or nonmelanocytic. Pattern analysis is the method preferred by many expert dermoscopists to diagnose melanocytic lesions and to differentiate benign melanocytic lesions from malignant melanoma. Pattern analysis refers to the simultaneous assessment of the diagnostic value of all dermoscopy features shown by the lesion.

In general terms, benign lesions have few colours, a regular structure and are symmetrical in pattern. Melanomas often have several colours, disordered structure and asymmetry of pattern.

If pattern analysis appears too complicated, use the 3-point checklist to identify malignant pigmented lesions.

Benign melanocytic lesions

Global features

• Reticular pattern (diffuse network)
• Globular pattern (shades of brown)
• Homogeneous pattern (diffuse colour)
• Starburst pattern (uniform peripheral radial streaks, dots or globules)
• Parallel pattern (along furrows; palms & soles only)

Reticular pattern

Globular pattern

Homogeneous pattern

Starburst pattern

Local features

• Pigment network, evenly spaced, fading out
• Dots/globules distributed regularly
• Streaks distributed regularly
• Central hypopigmentation
• Symmetrical blotches
• Comma-like regular vasculature
• On face: regular pseudonetwork
• On palms/soles: Parallel furrow, lattice-like or fibrillar pattern

Fading pigment network	Regular globules	Regular streaks	Central hypopigmentation
Symmetrical blotches	Comma-like vasculature	Symmetrical blotches/network	Regular pseudonetwork
Parallel furrow pattern	Parallel lattice pattern	Parallel fibrillar pattern	Parallel diffuse pattern

Melanoma

Global features

• Multicomponent pattern (3 or more patterns)
• Parallel pattern (along ridges; palms & soles only)

Global features of melanoma

Multicomponent pattern

Multicomponent pattern

Multicomponent pattern

Parallel ridge pattern

Local features

• Atypical pigment network (branched, broken-up, thickened, asymmetrical)
• Dots/globules distributed irregularly and of different sizes and shapes
• Asymmetrical blotches (featureless colours)
• Focal irregular streaking or peripheral linear projections (radial streaming and pseudopods)
• Five or six colours (black, brown, tan, grey, blue, red, white)
• Blue-white veil over part of the lesion
• White scar-like depigmentation
• Blue pepper-like granules
• Irregular linear or dotted vessels, or polymorphous vascular pattern especially with milky-red areas
• On face: grey dots, pseudonetwork, rhomboidal structures, asymmetrical pigmented follicles, annular-granular structures
• On palms/soles: parallel ridge, irregular

Local features of melanoma

Atypical pigment network	Irregular globules	Asymmetrical blotches	Focal irregular streaking
Five to six colours	Blue-white veil	Scar-like depigmentation	Blue pepper granules
Irregular vessels	Melanoma on the face	Parallel ridge	Asymmetrical blotches, dots

Activity

Practice pattern analysis by identifying global and local features in melanocytic lesions.

 

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