Abcd rule, dermatoscopic

Definition
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Semiquantitative evaluation scheme of vital histology for the calculation of a dermoscopic value (DPW) for the grading of a pigment lesion with regard to its malignancy.

General information
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Evaluation: The criteria of the dermatoscopic ABCD rule (asymmetry, boundary, color, differential structure) are generally recognizable in overview images, i.e., at about 10x magnification, and are therefore to be referred to as dermatoscopic characteristics, factors for calculating the number of pointsm see Table.
- DPW < 5.45: Benign pigmented malignancy very likely.
- DPW > 5.45: Malignant melanoma very likely (borderline range: 4.75-5.45).
Diagnostic accuracy is reported to be 92.2%. About 9.7% of benign melanocytic nevi are misdiagnosed as malignant according to the dermoscopy rule.

Notice. Additional information, e.g., whitish regressive areas, vascular patterns, or other pigmentary features, should be used if the DPW is between 4.75 and 5.45.

Caveat. Amelanotic or nodular melanomas may also have low scores (< 5.45).

Literature
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Proud W, Braun-Falco O, Bilek P, Landthaler M, Burgdorf WHC, Cognetta AB (2002) Color atlas of dermatoscopy. Blackwell, Berlin

Tables
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Feature	Peculiarity	Score	factor*
Asymmetry	in 0, 1 or 2 axes	0-2	x 1,3
Limitation	Abrupt termination of the pigment pattern in 0 to 8 segments	0-8	x 0,1
Colour	white, red, light brown, dark brown, blue grey, black	1-6	x 0,5
Differential structure	Network, unstructured areas, dots, plaice, stripes	1-5	x 0,5

* Coefficient for the calculation of the dermoscopy point value (DPW)