Dermoscopy (also called dermatoscopy, epiluminescence microscopy, and surface microscopy) is a method of examining the skin and its underlying structures using handheld magnification. Just as light reflects off the surface of a lake, distorting the view of the rocks and fish, so too does the stratum corneum reflect light off the skin, preventing the structures below from being seen clearly by the naked eye. Dermoscopy uses polarized light or nonpolarized light with a liquid/gel interface to circumvent this problem. The use of nonpolarized light requires applying a liquid/gel medium onto the skin and then placing the lens directly onto the surface of the skin, creating a tight seal, whereas polarized light does not require direct skin contact. Both methods reduce the glare from the stratum corneum and result in an enhanced microscopic (standard 10× magnification) and highly resolute image of the structures just beneath the surface of the skin. With this newly improved vision, the clinician is in a much better position to assess and diagnose various dermatologic lesions, mites, and diseases. The proper evaluation of the magnified image is an invaluable tool that provides a clinician with greater diagnostic accuracy, sensitivity, and specificity. Vestergaard et al. found a relative diagnostic odds ratio for melanoma to be 9.0 (95% CI 1.5 to 54.6, p = 0.03) and a difference in sensitivity of 0.18 (95% CI 0.09 to 0.27, p = 0.002) with no significant decrease in specificity.1 In other words, the odds of diagnosing a melanoma were nine times greater when trained clinicians used dermoscopy, as compared with naked eye examination. Further, they overlooked or missed fewer true positive diagnoses of melanoma (sensitivity), without increasing the number of benign lesions incorrectly diagnosed as melanoma (specificity). One can correctly assume that this advantageous tool allows clinicians to more confidently determine which lesions should be considered for a second opinion or biopsy. Studies have found that, with appropriate use, dermoscopy can decrease the number of unnecessary excisions up to nearly 40%.2 The benefit of mastering dermoscopy, coupled with its simple and noninvasive nature, unequivocally proves to be an important and useful tool for clinicians. By decreasing unnecessary biopsies and excision of benign skin lesions mimicking malignancies, and increasing accurate diagnosis of a variety of lesions (including malignant melanomas, nonpigmented malignant neoplasms, papulosquamous conditions, and scabies),3 dermoscopy ultimately provides improvement in patient management and welfare. Whether you are getting ready to take on dermoscopy for the first time or have been using dermoscopy for some time, it is good to review the differences between different dermatoscopes. While the technologies have improved immensely, the critical differences between contact nonpolarized dermoscopy (CNPD) and contact polarized dermoscopy (CPD) are the same. When thinking about what type of dermatoscope to use, there are a few general and technical considerations to keep in mind. Types of Dermatoscopes In general, nonpolarized dermatoscopes:
Chapter 2 Equipment
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