Reflectance confocal microscopy as a second-level examination in skin oncology improves diagnostic accuracy and saves unnecessary excisions: a longitudinal prospective study

Background Dermatoscopy increases both the sensitivity and specificity of melanoma diagnosis. Reflectance confocal microscopy (RCM) is a noninvasive technique that complements dermatoscopy in the evaluation of equivocal lesions at cellular resolution. Objectives To determine prospectively the potential impact of confocal microscopy when implemented in a routine melanoma diagnosis workflow. Methods Patients referred to a single melanoma clinic were consecutively enrolled. At dermatoscopy, patients were referred to one of the following pathways: (i) no further examination or (ii) RCM examination. On examination atypical lesion(s) were referred for either (a) RCM documentation (lesions with consistent suspicious clinical/dermatoscopic criteria, already qualified and scheduled for surgical excision) or (b) RCM consultation for equivocal lesions, where RCM diagnosis would determine lesion definite outcome (excision or digital follow-up). Results Reflectance confocal microscopy examination was performed for 41% of 1005 patients enrolled. In two-thirds of these cases RCM influenced the lesion outcome. The systematic application of RCM for equivocal lesions saved over 50% of benign lesions from unnecessary excision. The number needed to excise a melanoma was 6.8 with RCM examination, compared with a hypothetical 14.6 without RCM evaluation. Conclusions Reflectance confocal microscopy as a second-level examination to dermatoscopy proved to be highly accurate in diagnosis and reduced the number of unnecessary excisions. Improved accuracy, considering that RCM enabled the detection of the six melanomas (2%) in the group of 308 lesions eligible for follow-up, also minimizes the risk of referring a melanoma to digital dermatoscopy monitoring, and potentially losing the patient to follow-up.