Mitotic rate is recognized as having independent prognostic significance in melanoma survival. However, the clinical characteristics of rapidly growing tumors remain unclear. In this cross-sectional study, Shen et al found that melanomas occurring in men, in elderly patients, or on the head and neck all had a higher mitotic rate. Amelanotic tumors, those noted to be rapidly growing, and those discovered by the patients also had higher mitotic activity. Mitotically active melanomas were more often seen in the setting of chronic solar field damage. A high index of suspicion is warranted when patients report a history of morphologic change and rapid growth in this clinical setting.