Abcd rule

Clinical rule for assessing the dignity of pigmented skin lesions or melanocytic nevi according to the following criteria:

• A = Asymmetry (unequal halves on both sides of an imaginary midline)
• B = Border irregularity (irregular border)
• C = Color variation, especially occurrence of black, gray, red tones, fading of individual parts (most important criterion)
• D = Diameter: more than 5 mm or growth in size.

If all four criteria are met, a pigmented skin lesion is highly suspicious for malignant melanoma. As a 5th parameter, exophytic growth (E = Elevation) can be included in the evaluation of the tumor.

• E = Elevation

Notice. The ABCD rule is generally accepted as a guideline for dignity criteria of melanocytic nevi. However, it often fails in nodular malignant melanoma, but especially in amelanotic tumors.

Wilhelm Stolz introduced the ABCD rule for reflected light microscopy, see ABCD rule, dermatoscopic

1. Chamberlain AJ et al (2003) Nodular melanoma: Patient`s perceptions of presenting features and implications for earlier detection. J Am Dermatol 48: 694-701