Differences Between Polarized Light Dermoscopy and Immersion Contact Dermoscopy for the Evaluation of Skin Lesions

Abstract

Dermoscopy has proven to be a valuable tool in the diagnosis of pigmented and nonpigmented skin lesions,^1,2 increasing the clinical diagnostic accuracy^3,4 and improving physicians' confidence in their clinical diagnosis.⁵ Until recently, dermoscopes used only nonpolarized light sources to illuminate the skin, requiring a liquid interface and direct contact between the scope and the skin. With this approach, the amount of light reflected, refracted, and diffracted at the skin surface was reduced, thereby allowing the observer to visualize structures below the stratum corneum. Nonpolarized dermoscopes have been the standard for dermoscopy training and courses and for capturing dermoscopic images for textbooks and manuscripts. However, new commercially available dermoscopes that exploit the properties of cross-polarized light have been recently introduced.^6-8 Unlike nonpolarized light dermoscopy (NPD), polarized light dermoscopy (PD) allows visualization of deep skin structures without the necessity of a liquid interface or direct skin contact with the instrument.⁹ These instruments offer the capability of viewing the skin with (polarized light contact dermoscopy [PCD]) or without (polarized light noncontact dermoscopy [PNCD]) a liquid interface and direct skin contact.