Diagnostic Accuracy of Polarized and Ultraviolet Fluorescence-Induced Dermoscopy in Scarring and Nonscarring Alopecias: a Retrospective Observational Multicentric Study

Introduction: There is growing evidence that ultraviolet-induced fluorescence (UVF) dermoscopy may improve diagnostic accuracy in non-neoplastic dermatoses, yet data on hair disorders are scarce. The aim of this observational retrospective study was to compare the accuracy of polarized dermoscopy and UVF-dermoscopy in characterizing and distinguishing scarring and nonscarring alopecias. Methods: A total of 84 patients were enrolled, with 43 and 41 patients suffering from nonscarring and scarring alopecias, respectively. Analyzed variables included scarring findings (i.e., dotted/globular, structureless or perifollicular bright white areas on both polarized and UVF-dermoscopy) and follicular unit (i.e., hair or follicular ostia, with the latter appearing as empty follicular openings and follicular red/blue fluoresce on polarized and UVF-dermoscopy, respectively). Comparative analysis between polarized and UVF-dermoscopy in detecting the abovementioned features and differentiating scarring from nonscarring alopecias were performed, also assessing possible differences according to the skin tone. Interobserver agreement was evaluated for both dermoscopic settings. Results: UVF-dermoscopy was superior (p < 0.01) to polarized dermoscopy in detecting follicular ostia and white bright areas in general and fair-skinned patients, while only follicular ostia were better seen under this setting in skin of color. Additionally, UVF-dermoscopy was found to be more accurate (p < 0.01) in differentiating nonscarring from scarring alopecias when considering all and light phototypes. Finally, Kappa values were 0.57 and 0.83 for polarized and UVF-dermoscopy, respectively. Conclusions: UVF-dermoscopy may be a valuable and reliable complementary tool in differentiating scarring and nonscarring alopecias, especially in light phototypes.