10.5826/dpc.1203a119
text/xml
2160-9381
2185
en
Sam Polesie
https://creativecommons.org/licenses/by-nc/4.0
Dermatology Practical & Conceptual
Polarized light
Iridescent changes observed during dynamic cross-polarized dermoscopy
Text.Serial.Journal
https://dpcj.org/index.php/dpc
Image Letter
2022-07-28
2021-11-23
2022-07-28
2022-09-15
e2022119
Dermatol Pract Concept
Sam Polesie
2022/07/28
10.5826/dpc.1203a119
e2022119
Department of Dermatology and Venereology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden AND Region Västra Götaland, Sahlgrenska University Hospital, Department of Dermatology and Venereology, Gothenburg, Sweden
2160-9381
Polarized light
en
e2022119
Draghici C, Vajaitu C, Solomon I, Voiculescu VM, Popa MI, Lupu M. The Dermoscopic Rainbow Pattern - A Review of the Literature. Acta Dermatovenerol Croat. 2019 Jun;27(2):111-115.
Iridescent changes observed during dynamic cross-polarized dermoscopy
https://dpcj.org/index.php/dpc/article/download/2185/1683
                    Dermatology Practical & Conceptual


                   Iridescent Changes Observed During
                   Dynamic Cross-polarized Dermoscopy
 John Paoli1,2, Lykke Barck1,2, Eva Johansson Backman1,2, Ashfaq Marghoob3, Sam Polesie1,2


1 Department of Dermatology and Venereology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg,
  Sweden
2 Region Västra Götaland, Sahlgrenska University Hospital, Department of Dermatology and Venereology, Gothenburg, Sweden
3 Department of Dermatology, Memorial Sloan Kettering Cancer Center, New York, NY, USA



Citation: Paoli J, Barck L, Backman EJ, Marghoob A, Polesie S. Iridescent changes observed during dynamic cross-polarized dermoscopy.
Dermatol Pract Concept. 2022;12(3):e2022119. DOI: https://doi.org/10.5826/dpc.1203a119
Accepted: November 24, 2021; Published: July 2022
Copyright: ©2022 Paoli 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: John Paoli, M.D., Ph.D, Department of Dermatology and Venereology, Sahlgrenska University Hospital, Institute of
Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gröna Stråket 16, 413 45, Gothenburg, Sweden Tel: +46(0) 730 40 40 44,
E-mail: john.paoli@gu.se




Case Presentation                                                       dermoscopy. It has been described in several different skin
                                                                        tumors (eg Kaposi sarcoma, hemosiderotic dermatofibroma,
A 60-year-old male with skin phototype IV from Africa and               angiokeratoma, aneurysmal atypical fibroxanthoma, mela-
a history of Kaposi sarcoma on his foot presented with a                noma and basal cell carcinoma) and other skin conditions
rapidly growing, 6.5-mm, bluish-purple nodule on his back.              (eg stasis dermatitis, lichen planus and scars) [1]. It is sur-
Cross-polarized dermoscopy using a DermLite DL4 (3Gen)                  mised that polarized light passing through slits created by
coupled with an iPhone XS Max (Apple) revealed a ‘rainbow               parallelly aligned collagen bundles or vessels may cause the
pattern’ on a structureless red background. By rotating the             light to separate into different wavelengths [2]. Although
dermoscope without moving the smartphone during imaging,                the exact structures that actually cause the optical interfer-
also known as dynamic cross-polarized dermoscopy, the color             ence are unknown, the observed phenomenon is called iri-
distribution within the rainbow pattern changed substantially           descence. By applying dynamic cross-polarized dermoscopy,
(Figure 1, Supplementary Video 1). The lesion was excised               we demonstrate that the iridescence changes with the angle
and histopathologically confirmed as Kaposi sarcoma.                    of polarization. This angular dependence of cross-polarized
                                                                        light has also been demonstrated previously by Marghoob
                                                                        et al on shiny white lines, which are only visible with the
Teaching point
                                                                        dermoscope positioned at specific angles.
The metaphoric term ‘rainbow pattern’ is used to describe
polychromatic structureless areas only seen with polarized




Image Letter | Dermatol Pract Concept. 2022;12(3):e2022119                                                                                1
    Figure 1. (A) Clinical presentation of a case of Kaposi sarcoma. (B) Iridescence or ‘rainbow pattern’ observed during cross-polarized
    dermoscopy at a specific angle. (C) Modified iridescence shown after rotating the dermoscope 90°.




References                                                               Supplementary Video Legend
1. Elmas OF, Mayisoglu H, Celik M, Kilitci A, Akdeniz N. Dermo-          Supplementary Video 1. The iridescence or ‘rainbow pat-
   scopic rainbow pattern: A strong clue to malignancy or just a light
                                                                         tern’ changes substantially while rotating the dermoscope
   show? North Clin Istanb. 2020;7(5):494–498. DOI: 10.14744/
                                                                         relative to the smartphone camera (dynamic cross-polarized
   nci.2020.32656. PMID: 33163886. PMCID: PMC7603844.
2. Draghici C, Vajaitu C, Solomon I, Voiculescu VM, Popa MI,             dermoscopy), thus demonstrating the angular dependence of
   Lupu M. The Dermoscopic Rainbow Pattern - A Review of the             polarization.
   Literature. Acta Dermatovenerol Croat. 2019;27(2):111–115.
   PMID: 31351506.




2                                                                              Image Letter | Dermatol Pract Concept. 2022;12(3):e2022119
