Non-invasive optical methods for melanoma diagnosis

Cutaneous melanoma is one of the most common malignancies with increased incidence in the past few decades, making it a significant public health problem. The early diagnosis of melanoma is a major factor in improving patient's survival. The traditional pathway to melanoma diagnosis starts with a visual diagnosis, followed by subsequent biopsy and histopathologic evaluation. Recently, multiple innovative optical technology-based methods, including dermoscopy, reflectance confocal microscopy, optical coherence tomography, multiphoton excited fluorescence imaging and stepwise two-photon excited fluorescence (dermatofluoroscopy), have been developed to increase the diagnostic accuracy for the non-invasive melanoma diagnosis. Some of them have already been applied to real-life clinical settings, others require more research and development. These technologies show promise in facilitating the diagnosis of melanoma since they are non-invasive, sensitive, objective and easy to apply. Diagnostic accuracy, detection time, portability and the cost-effectiveness of the device are all aspects that need to be improved. This article reviews the method of these emerging optical non-invasive diagnostic technologies, their clinical application, their benefits and limitations, as well as their possible future development.