The ABCD mnemonic for cutaneous melanoma indicates that tumor diameter (D) is typically greater than 6 mm.
To determine the distribution of preoperative tumor diameter in a midwestern United States general dermatology practice–based case series.
Patient records were reviewed for preoperative maximal tumor diameter for primary cutaneous melanomas diagnosed between January 1, 2006, and February 1, 2012.
Of 116 tumors for which preoperative measures were available, 38 (32.8%) had a diameter of 6 mm or less. Of these 38 small-diameter (≤6 mm) cases, tumor invasion occurred in 26 (68.4%), compared with 36 of the 78 (46.2%) larger-diameter (>6 mm) cases. Small-diameter tumors were significantly more common in patients younger than 60 and almost twice as common in women than men.
Almost one-third of evaluable tumors in this general dermatology practice–based setting had a preoperative diameter of 6 mm or less, and two-thirds of these small-diameter cases were invasive. The diameter criterion of greater than 6 mm in the ABCD mnemonic is precariously insensitive for a public message.