Three-point checklist

Learning objectives
Introduction
Symmetry
Network
Blue-white structures
Activity

Learning objectives

• Describe and use the 3-point checklist for evaluating pigmented skin lesions by dermoscopy

Introduction

The dermoscopy 3-point checklist for early detection of skin cancer is fairly easy to learn and has a high sensitivity for melanoma. (1) There a high likelihood of malignancy (melanoma or basal cell carcinoma) if a pigmented skin lesion has any two of these criteria. The 3-point checklist has been designed to allow non-experts not to miss detection of melanomas. However, it is not as specific as pattern analysis (described in a later section).

• Asymmetry: asymmetry of colour and structure in one or two perpendicular axes
• Atypical network: pigment network with irregular holes and thick lines
• Blue-white structures: any type of blue and/or white colour, i.e. combination of blue-white veil and regression structures

The main aim of the 3-point checklist is to determine whether the lesion being examined should undergo a biopsy. It does not an require accurate diagnosis to be made as the finer features of the lesion are not examined.

Score = 0 Benign	Score = 1 Benign	Score = 2 Malignant	Score = 3 Malignant
Symmetrical, uniform network, no blue-white structures.	Mild asymmetry of structure, no network, no blue-white structures.	Marked asymmetry of structure, network is ok, subtle greyish blue structure (arrow).	Mild asymmetry of structure, broad dark grey network which has blue-grey veil.

Symmetry

The following lesions demonstrate approximate symmetry of colour and structure. Shape is not considered.

Cherry angioma	Compound naevus	Compound naevus	Cellular naevus
Solar lentigo	Plantar naevus	Benign naevus	Seborrhoeic keratosis

The lesions below demonstrate asymmetry of colour or structure in one or two axes. Not all asymmetrical lesions are malignant.

Melanoma in situ	Melanoma in situ	Invasive melanoma	Basal cell carcinoma
Plantar naevus	Seborrhoeic keratosis	Lentigo simplex	Congenital naevus

Network

The following lesions are considered to have typical pigment network.

Junctional naevus	Ephilis	Benign naevus	Junctional naevus
Ink spot naevus	Plantar naevus	Facial lentigo	Dermatofibroma

The lesions below have atypical pigment network, with irregular holes and thick lines (broadened network). Streaming or pseudopods would also be considered atypical. Not all lesions with atypical network prove to be malignant.

Irregular pigment network: black arrows to broadened network, asterisk to streaming

Melanoma	Lentigo maligna	Melanoma in situ	Lentigo maligna
Melanoma	Lentigo maligna	Lentigo maligna	Atypical naevus

Blue-white structures

Blue-white structures can refer to any type of blue and/or white colour, i.e. combination of blue-white veil and regression structures, as shown in the following pictures. The colour can be subtle. Not all lesions with blue-white structures are malignant.

Melanoma	Basal cell carcinoma	Melanoma	Lentigo maligna
Congenital naevus	Blue naevus	Dysplastic naevus	Dysplastic naevus

Activity

Practice dermoscopy, evaluating skin lesions using the 3-point checklist.

 

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