The role of reflectance confocal microscopy in the diagnosis and management of pigmentary disorders: A review.

BACKGROUND: Reflectance confocal microscopy (RCM) has quickly transitioned from a research tool to an adjunct diagnostic bedside tool, providing the opportunity for noninvasive evaluation of skin lesions with histologic resolution. RCM is an optical imaging technique that uses near-infrared excitation wavelengths and safe low-power lasers. En-face images of different skin layers (up to the superficial dermis) are acquired in grayscale based on the reflective indices of tissue components. Melanin has the highest reflective index (contrast) and appears bright on RCM.

AIMS: We present a review of the current literature on the use of RCM in the diagnosis and management of pigmentary disorders.

METHODS: We reviewed PubMed and Ovid Medline databases from January 2000 to June 2021, using MeSH key terms: "reflectance confocal microscopy, confocal laser scanning microscopy, pigmentary disorders, treatment, melasma, vitiligo, freckles, solar lentigo, lentigo, tattoo, complications, melanoma, skin cancers, pigmented lesions, post inflammatory, melanin, photoaging" to identify studies and review articles discussing the use of RCM in the diagnosis and management of pigmentary disorders.

RESULTS: RCM findings of pigmentary disorders were divided into the following categories: (1) disorders of increased pigmentation (post-inflammatory hyperpigmentation, melasma, Riehl's melanosis, solar lentigines, ephelides, hori nevus, naevus of Ota, café-au-lait macules, melanocytic nevus, melanoma, nevus spilus, labial mucosal melanosis, and mucosal melanoma), (2) disorders of decreased pigmentation or depigmentation (post-inflammatory hypopigmentation, vitiligo, nevus depigmentosus, halo nevus), and (3) exogenous pigmentation (tattoo, ochronosis).

CONCLUSION: RCM has been explored and proven valuable for the evaluation and management of pigmentary disorders including melasma, vitiligo, solar lentigines, tattoo, and tattoo-related complications.