Diagnostic methods

Created 2017.

Chaos and clues

The dermatoscopic method known as Chaos and Clues was first described by Dr Cliff Rosendahl. It helps the observer to decide if a lesion should be excised. 

With certain exceptions, a malignant (or at least, suspicious) pigmented skin lesion can be identified with confidence on dermatoscopy if it has:

• Chaos 

PLUS

• ≥1 clue to malignancy 

Chaos is defined as asymmetry of structure/colour and ≥2 patterns.

The 9 clues to malignancy are:

1. Eccentric structureless area
2. Thick lines reticular or branched
3. Grey or blue structures
4. Black dots or clods, peripheral
5. Lines radial or pseudopods, segmental
6. White lines
7. Polymorphous vessels
8. Large polygons
9. Lines parallel, ridges (palms or soles)

Three point checklist

If two of the three features below are present, consider excision.

1. Asymmetry of colour and structure in one or two perpendicular axes
2. Atypical network (irregular holes and thick lines)
3. Blue-white structures: any type of blue and/or white colour 

Four point checklist

Total score >2 points indicates lesion is suspicious.

• Asymmetry of colour and structure in first axis — 1 point
• Asymmetry of colour and structure in second axis — 1 point
• Irregular or thick pigment network  — 1 point
• Blue-white structure  — 1 point

TADA