Role of In Vivo Reflectance Confocal Microscopy in the Analysis of Melanocytic Lesions

Worldwide melanoma incidence and mortality are increasing (1). Despite the ongoing research, advanced melanoma is still incurable; therefore, the most appropriate solution seems to be early detection combined with complete surgical excision (2). Since the diagnostic protocol of suspicious lesions includes a complete excision with safety margins (2), the problem of unnecessary scarring is significant. The real challenge in this case is to have a properly formulated diagnosis before acquiring a biopsy. Currently available non-invasive techniques are coherence tomography, digital dermoscopy, and reflectance confocal microscopy. All these techniques allow for a presumptive diagnosis, but the most promising results are provided by reflectance confocal microscopy. Reflectance confocal microscopy (RCM) is an optical imaging technique that uses a laser diode as a source of coherent monochromatic light which penetrates the tissue and illuminates a single point. Light from the stimulated section is reflected and passes through a filter, thereby forming the image on the detector. This filter enables selective excitation of a particular point on which focus is achieved and rejects reflection from the out-of-focus area, thus obtaining a "confocal" image. Contrast is the result of differences in the refractive index of the cell organelles and microstructures, resulting in white structures on a black background. This technique allows, as opposed to conventional light microscopy, the analysis of sections obtained at a bi- or tri-dimensional level and controlling the depth of the field, permitting out-of-focus artifacts to be eliminated. In dermatology, this technique is useful for both clinical and research purposes. It is the only technique that allows horizontal viewing of the skin up to the superficial dermis (approximately 300 mm, at a cellular level resolution (0.5-1.0 μm in the lateral dimension and 4.0-5.0 μm in the axial dimension) (3). It allows both in vivo and ex vivo diagnosis, while providing the possibility for long-term monitoring. It has proved to be especially valuable for in vivo examinations of melanocytic lesions, whereas melanin and melanosomes are a powerful source of contrast, allowing the individualization of melanocytic cells (4). We report the case of a 65-year-old Caucasian woman who presented to the Dermatology Department of University of Modena and Reggio Emilia, Italy, for the examination of an atypical lesion, of unknown history, localized i