Other algorithms for melanocytic lesions

Learning objectives
Introduction
ABCD rule
Menzies method
7-point rule
Activity

Learning objectives

• Describe several algorithms for evaluating melanocytic lesions by dermoscopy

Introduction

The first step algorithm identifies whether a lesion is melanocytic or nonmelanocytic. Various algorithms may be used to distinguish benign melanocytic lesions from malignant melanoma:

• ABCD rule
• Menzies method
• 7-point rule

If these algorithms appear too complicated, use the 3-point checklist to identify malignant pigmented lesions.

ABCD rule

The ABCD rule (Stolz method) is used for the dermoscopic differentiation between benign melanocytic lesions and melanoma. The likelihood of melanoma depends on adding up the scores for different features as shown below.

Criteria	Score  X	Factor  =	Results
Asymmetry In perpendicular axes: contour, colours and structures	0 - 2	1.3	0 - 2.6
Borders 8 segments: abrupt ending of pigment pattern	0 - 8	0.1	0 - 0.8
Colours White, red, light-brown (tan), dark-brown, blue-grey, black	1 - 6	0.5	0.5 - 3.0
Differential structural components	1 - 5	0.5	0.5 - 2.5
Total score	Benign		<4.76
	Suspicious		4.76-5.45
	Melanoma		>5.45

Asymmetry = 0	Asymmetry = 1	Asymmetry = 2
Borders = 0	Borders = 4	Borders = 8
Colours = 1 Tan	Colours = 3 Tan, dark brown, black	Colours = 5 White, red, tan, dark brown, black

Blum's modified ‘ABC-point list’ is simpler to use:

• A – asymmetry of outer shape or differential structures inside the lesion in at least 1 axis
• B – the abrupt cutoff of network at the border in at least one quarter of circumference
• C – 3 or more colors
• D – 3 or more differential structures
• E – noticed change (evolution) in the last 3 months

Menzies method

Menzies method to distinguish the dermoscopic features of benign melanocytic lesions from melanoma.

Negative features (benign lesions):

• Symmetrical pattern (colours, structure)
• Single colour

Symmetrical pattern

Symmetrical pattern

Single colour

Single colour

Positive features (melanoma):

• Blue-white veil
• Multiple brown dots
• Pseudopods
• Radial streaming
• Scar-like depigmentation
• Multiple (5-6) colours
• Multiple blue/grey dots
• Broadened network

Blue-white veil	Multiple brown dots	Pseudopods	Radial streaming
Scar-like depigmentation	Multiple colours (5)	Multiple blue/grey dots	Broadened network

Seven-point rule

7-point checklist for the dermoscopic differentiation between benign melanocytic lesions and melanoma (scores in brackets). The scores should be added up. Three or more indicates melanoma.

1. Atypical pigment network (2)
2. Blue-whitish veil (2)
3. Atypical vascular pattern (2)
4. Irregular streaks (1)
5. Irregular dots/globules (1)
6. Irregular blotches (1)
7. Regression structures (1)

Atypical pigment network	Blue-whitish veil	Atypical vascular pattern	Irregular streaks
Irregular dots/globules	Irregular blotches	Regression structures

Activity

Find the evidence to support the use of the algorithms. Which is the best?

 

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