Border abruptness in pigmented skin lesions

'Border abruptness' is a concerning feature.

The decision algorithm Chaos and Clues, like most published dermatoscopic decision algorithms for pigmented skin lesions, relies primarily on asymmetry to flag suspicion of malignancy.

If asymmetry is detected, the lesion is examined carefully for clues to malignancy, and if one or more clues are detected, the lesion is considered for excision biopsy unless an unequivocal diagnosis of seborrhoeic keratosis can be made.

Dermatoscopic chaos is defined as asymmetry of structure and/or colour and it reflects the chaotic behaviour of malignant tissue.