IN-VIVO CONFOCAL SCANNING LASER MICROSCOPY OF HUMAN SKIN - MELANIN PROVIDES STRONG CONTRAST

Confocal scanning laser microscopy of live human skin was performed to investigate the correlation of in vivo cellular and morphologic featu res to histology, the effect of wavelength on imaging, and the role of melanin as a contrast agent. We built a video-rate confocal scanning laser microscope for in vivo imaging of human skin. Using a 100 x micr oscope objective, we imaged high-contrast optical ''sections'' of norm al skin, vitiliginous skin, and a compound nevus. In vivo ''confocal h istology'' correlated well with conventional histology. The maximum im aging depth increased with wavelength: the epidermis was imaged with v isible 400-700-nm wavelengths; the superficial papillary dermis and bl ood cells (erythrocytes and leukocytes) in the deeper capillaries were imaged with the near infrared 800-900-nm wavelengths. For confocal re flectance imaging, melanin provided strong contrast by increased backs cattering of light such that the cytoplasm in heavily pigmented cells imaged brightly. In vivo confocal microscopy potentially offers dermat ologists a diagnostic tool that is instant and entirely non-invasive c ompared to conventional histopathology.