Because recommendations for skin cancer treatment depend on lesion size, it is crucial to begin with an accurate measurement. A recent study suggests that although dermatologists appear to estimate pigmented lesion sizes without using rulers or landmarks more accurately than medical students and internal medicine residents, using a ruler provides significantly more accurate measurements.

Previous studies have examined the relative prowess of dermatologists and general practitioners in assessing and triaging pigmented lesions without a ruler. In perhaps the first study of its kind, researchers led by June K. Robinson, M.D., of Northwestern University Feinberg School of Medicine, pitted dermatologists against internal medicine residents and medical students in various testing scenarios. The research letter appeared in the December 27, 2017, online version of JAMA Dermatology.