Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2022;12(4):e2022250 1 Not All Polarized-light Dermatoscopes May Display Diagnostically Critical Polarizing-specific Features Chin Whybrew1, Pawel Pietkiewicz2, Ihor Kohut3, Justin C. Chia4, Bengu Nisa Akay5, Cliff Rosendahl6,7 1 GP, Stoke Road Surgery, Bishops Cleeve, Cheltenham, UK 2 General and Oncological Surgery Clinic I, Greater Poland Cancer Center, Poznan, Poland 3 Skin Health Center, Ternopil, Ukraine 4 Division of Dermatology, University of Calgary, Calgary, Alberta, Canada 5 Ankara University Medicine Faculty, Department of Dermatology, Ankara, Turkey 6 General Practice Clinical Unit, Medical School, The University of Queensland, Australia 7 School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Key words: dermoscopy, dermatoscopy, shiny white structures, polarizing-specific white lines Citation: Whybrew C, Pietkiewicz P, Kohut I, Chia JC, Akay BN, Rosendahl C. Not all polarized-light dermatoscopes may display diagnostically critical polarizing-specific features. Dermatol Pract Concept. 2022;12(4):e2022250. DOI: https://doi.org/10.5826/ dpc.1204a250 Accepted: April 27, 2022; Published: October 2022 Copyright: ©2022 Whybrew et al. This is an open-access article distributed under the terms of the Creative Commons Attribution- NonCommercial License (BY-NC-4.0), https://creativecommons.org/licenses/by-nc/4.0/, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original authors and source are credited. Funding: None. Competing interests: None. Authorship: All authors have contributed significantly to this publication. Corresponding author: Cliff Rosendahl, General Practice Clinical Unit, Medical School, The University of Queensland, Larbonya Crescent, Capalaba, Queensland, Australia 4157. Phone: +61 419 769 970 Fax: +617 3245 3011 Email: cliff@omera.com.au Introduction Since the introduction of polarized-light dermatoscopes it has become evident that there are some fundamental differ- ences in image characteristics, in comparison to those pro- vided by non-polarized dermatoscopy [1]. Non-polarized dermatoscopy provides color rendition without dilution of colors such as gray and blue by polariz- ing filters, and it provides a clear display of white clods and dots (milia-like cysts) in seborrheic keratoses [1-3]. Polarized dermatoscopy on the other hand displays fea- tures not seen in non-polarized dermatoscopy, including shiny white structures/streaks [4] (defined as short, bright, white lines distributed in a parallel or orthogonal orienta- tion, which can only be seen with polarized dermatoscopy), four-dot clods (rosettes) and polarizing-specific structureless areas [4]. Each of these polarizing-specific features are known to have diagnostic relevance, but notably, it has been shown that shiny white structures/streaks can be critical in the di- agnosis of melanoma [5] and in a meta-analysis they have been shown to have the equal highest odds ratio (OR) of 6.7 for the diagnosis of melanoma, compared to pseudopods (equal), irregular pigmentation (OR 6.4), blue-white veil (OR 6.3) and peppering (OR 6.3) [4]. 2 Research Letter | Dermatol Pract Concept. 2022;12(4):e2022250 Case Presentation A 69-year-old woman with Fitzpatrick phototype-2 skin presented with a pigmented skin lesion on the ankle. Der- matoscopic examination with six different dermatoscopes revealed a chaotic pattern with clues to malignancy including white lines in non-polarized mode with all dermatoscopes, as well as shiny white lines/streaks in polarized mode with five dermatoscopes (Figures 1 and 2). Dermatopathology con- firmed superficial spreading melanoma in situ. Prior to biopsy, multiple images were taken with the six dermatoscopes coupled with 2 different camera devices. Be- cause polarizing-specific features can be angle-dependent, for image acquisition each dermatoscope was rotated each time it was used in polarizing mode to produce the greatest display of shiny white structures/streaks possible. Five dermatoscopes: Heine DELTA 20T, and Heine DELTAone (Heine Optotechnik GmbH & Co. KG), DermLite DL4 (3Gen, Inc.), Opticlar (Albert Waeschle Ltd) and Illuco IDS 1100 (Illuco Co. Ltd.) displayed shiny white structures/streaks in polarized mode, with some ap- parent variations in intensity, distinctly different from the same device in non-polarized mode. The Heine DELTA 30 (Heine Optotechnik GmbH & Co. KG) did not display shiny white structures/streaks in polarized mode, the images be- ing essentially the same as produced in non-polarized mode (Figures 1 and 2). Figures 1-2 are labelled to display collages of polarized and non-polarized dermatoscopic images acquired with an iPhone 6 (Figure 1) and a Nikon Coolpix 4500 (Figure 2). No image manipulation has been performed other than cropping. The authors all assert that the features demonstrated with respect to the Heine DELTA 30 are consistent with those observed by each of them in clinical practice. Conclusions Clinicians are invited to independently test these findings, as it is important for dermatoscopists to be cognizant of the characteristics of the instruments they use due to potential impact on diagnostic performance. Acknowledgement We acknowledge Dr Mohammadreza Rahimpour whose original observations in 2020 initiated this assessment. Figure 1. Polarized and non-polarized images of a superficial spreading melanoma in situ, acquired with 6 different dermatoscopes coupled with an iPhone 6 camera. All photographs were taken by the same photographer (author CW) and are displayed without manipulation other than cropping. Research Letter | Dermatol Pract Concept. 2022;12(4):e2022250 3 References 1. Benvenuto-Andrade C, Dusza SW, Agero ALC, et al. Differences Between Polarized Light Dermoscopy and Immersion Contact Dermoscopy for the Evaluation of Skin Lesions. Arch Derma- tol. 2007;143(3):329-338. DOI: 10.1001/archderm.143.3.329. PMID: 17372097. 2. Pan Y, Gareau DS, Scope A, Rajadhyaksha M, Mullani NA, Marghoob AA. Polarized and Nonpolarized Dermoscopy: The Explanation for the Observed Differences. Arch Dermatol. 2008;144(6):828-829. DOI: 10.1001/archderm.144.6.828. PMID: 18559791. 3. Rosendahl C, Marozava A. Dermatoscopy and Skin Cancer. Banbury. UK.: SCION; 2019:pp 9-10. 4. Williams NM, Rojas KD, Reynolds JM, Kwon D, Shum-Tien J, Jaimes N. Assessment of Diagnostic Accuracy of Dermoscopic Structures and Patterns Used in Melanoma Detection: A Systematic Review and Meta-analysis. JAMA Dermatol. 2021;157(9):1078- 1088. DOI: 10.1001/ jamadermatol.2021.2845. PMID: 34347005. PMCID: PMC8339993. 5. Cohen YK, Elpern DJ, Wolpowitz D, Rosendahl C. Glowing in the dark: case report of a clue-poor melanoma unmasked by po- larized dermatoscopy. Dermatol Pract Concept. 2014;4(1):83-87. DOI: 10.5826/dpc.0401a14. PMID: 24520521. PMCID: PMC3919847. Figure 2. Polarized and non-polarized images of a superficial spreading melanoma in situ acquired with 6 different dermatoscopes coupled with a Nikon Coolpix 4500 camera. All photographs were taken by the same photographer (author CW) and are displayed without manipulation other than cropping.