Reflectance confocal microscopy in the diagnosis of pigmented macules of the face: differential diagnosis and margin definition.

In vivo reflectance confocal microscopy (RCM) is a noninvasive high-resolution skin imaging tool that has become an important adjunct to clinical exam, dermoscopy and histopathology assessment, in the diagnosis and management of pigmented macules of the face. The diagnosis of early stage lentigo maligna (LM) and lentigo maligna melanoma (LMM) is challenging and RCM improves the diagnostic accuracy in the differential diagnosis of LM with other macules of the face such as solar lentigo (SL), pigmented actinic keratosis (PAK), seborrheic keratosis (SK) and lichen planus-like keratosis (LPLK). Here we review the state-of-the-art of RCM morphologic descriptors, standardized terminology, and diagnostic algorithms for the RCM assessment of pigmented macules of the face including melanocytic, and nonmelanocytic lesions. Clinical applications of RCM are broad and include diagnosis, assessment of large lesions on cosmetically sensitive areas, directing areas to biopsy, delineating margins prior to surgery, detecting response to treatment and assessing recurrence. The present review is intended to summarize the application of RCM for the correct diagnosis of challenging pigmented facial macules and to evaluate its application in LM margin mapping during the pre surgical phase.