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:
Eccentric structureless area
Thick lines reticular or branched
Grey or blue structures
Black dots or clods, peripheral
Lines radial or pseudopods, segmental
White lines
Polymorphous vessels
Large polygons
Lines parallel, ridges (palms or soles)
Three point checklist
If two of the three features below are present, consider excision.
Asymmetry of colour and structure in one or two perpendicular axes
Atypical network (irregular holes and thick lines)
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
The Triage Amalgamated Dermoscopic Algorithm asks:
Angioma, dermatofibroma, seborrhoeickeratosis?
If yes, exclude from further analysis.
If no, any architectural disorder?
If yes, and one of the following 6 predictive factors should lead to excision or referral.