Redefining the number needed to excise.

The number needed to excise (NNE) is a metric used to convey the efficiency of dermatological practice by serving as a gauge for the diagnostic accuracy of melanoma. Rather than an NNE for melanoma alone, we assert that the NNE should measure all skin cancer types and we present data on NNE from two clinical sites demonstrating the utility and trends in NNE over time.