Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2023;13(3):e2023243 1 Pink-Red Fluorescence Observed in Ultraviolet-Induced Fluorescence Dermoscopy of Psoriatic Plaques Paweł Pietkiewicz1,2, Cristian Navarrete-Dechent3,4, Herman Mayisoğlu5, Gursharan Jolly6, Ömer Kutlu7, Enzo Errichetti8 1 Dermatology Private Practice, Poznań, Poland 2 Polish Dermatoscopy Group, Poznań, Poland 3 Department of Dermatology, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile 4 Melanoma and Skin Cancer Unit, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile 5 Department of Dermatology, Private Medicana Hospitals Bahçelievler, Istanbul,Turkey 6 Independent scholar, Poznań, Poland 7 Department of Dermatology & Venereology, Tokat Gaziosmanpasa University, School of Medicine, Tokat, Turkey 8 Institute of Dermatology, Santa Maria della Misericordia University Hospital, Udine, Italy Key words: dermatoscopy, ultraviolet radiation, psoriasis, porphyrins, diagnostics Citation: Pietkiewicz P, Navarrete-Dechent C, Mayisoğlu H, Jolly G, Kutlu Ö, Errichetti E. Pink-Red Fluorescence Observed in Ultraviolet-Induced Fluorescence Dermoscopy of Psoriatic Plaques. Dermatol Pract Concept. 2023;13(3):e2023243. DOI: https://doi.org/10.5826/dpc.1303a243 Accepted: May 26, 2023; Published: July 2023 Copyright: ©2023 Pietkiewicz 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: Paweł Pietkiewicz, Centrum Medyczne Zwierzyniecka, Zwierzyniecka Street 30/28, Poznań 60-814. Telephone: +48 602 133 503 E-mail: pietkiewicz.pp@gmail.com Introduction Psoriasis is a prevalent erythematous-desquamative derma- tosis with a substantial global mental and socioeconomic impact, affecting individuals of all ages. Among the pri- mary risk factors are genetic susceptibility, metabolic syn- drome, trauma, and stress. When examined under Wood’s lamp (peak wavelength 365nm), certain psoriatic plaques exhibit a red fluorescence [1-4]. Previous studies have re- ported an association between this finding and increased psoriasis severity [1,2]. Through the Stokes shift phenom- enon, ultraviolet-induced fluorescence dermoscopy (UVFD) offers a novel non-invasive diagnostic approach that visual- izes the UV-induced fluorescence of skin chromophores [5], with red fluorescence reported to be associated with the presence of protoporphyrin IX in the stratum corneum [3]. To date, the fluorescence patterns in psoriasis under Wood lamp have been mostly limited to clinical naked-eye exam- ination [1-3]. Here, we report pink-reddish fluorescence of psoriasis under UVFD. 2 Research Letter | Dermatol Pract Concept. 2023;13(3):e2023243 Case Presentation A 51-year-old man (Psoriasis Area Severity Index score 2.8) presented to the dermatology outpatient clinic with a soli- tary psoriatic plaque on his thigh present for a few weeks. In addition to the bright blue-greenish fluorescence of keratin and the blue background fluorescence of collagen and elastin fibers under UVFD, a distinctive pink-red fluorescence was identified in the central part of the lesion (Figure 1). In the reported case, this neon-like luminescence appeared to ema- nate from the scale near the elongated dermal papillae. Mi- crobiological culture collected from the patch was negative. The patient was treated with topical clobetasol and emol- lients with excellent response. Figure 1. (A) Clinical presentation of plaque psoriasis in a 51-year-old patient with a single lesion on a left thigh present for a few weeks. (B) Non-contact polarized dermoscopy of a suspect lesion reveals a silvery white-yellowish diffuse scale strongly adhering to the skin sur- face. Single hemorrhagic dots can be appreciated. (C) Ultraviolet-induced fluorescence dermoscopy (UVFD) reveals bright blue-greenish fluorescence of keratin, black centered hemorrhagic dots (high UV-absorbance of hemoglobin) and pink-red fluorescence of protoporphyrin IX within the stratum corneum. Blue stain is an artifact, likely associated with an emollient applied the other day. (D) Magnified image of non-contact polarized dermoscopy shows diffuse white-yellowish scale with roundish clods. Some of them enclose a centered hemorrhagic dot - a remnant of a dermal papillary vessel. (E) Magnified image with UVFD displays pink-red dots and clods surrounding the perivascular areas of elongated dermal papillae. Areas with greenish tint might correspond to serous deposits within the hyperkeratotic and parakeratotic scale. Research Letter | Dermatol Pract Concept. 2023;13(3):e2023243 3 Conclusions We have confirmed red fluorescence of psoriatic plaques observed with UVFD by Xie et al [2]. The exact source of epidermal porphyrins (protoporphyrin IX) remains unclear. The origin of protoporphyrin IX in psoriatic plaques might have either bacterial or non-bacterial origin. Despite a nega- tive microbiological culture, we cannot confidently exclude an infectious origin as the cause of fluorescence. The latter hypothesis might be supported by the previously unreported deposition of chromophores around the tortuous elongated vessels of acanthotic papillae (Figure 1E). Wang et al. re- ported that red fluorescence was positively correlated with psoriasis severity. Accordingly, besides diagnostic purposes, UVFD evaluation might also be helpful in assessing dis- ease outcomes/prognosis. However, further investigation is required to understand the mechanism of porphyrin depo- sition in psoriatic lesions, the spatial distribution of fluores- cence patterns, and how these phenomena relate to disease variants, severity and prognosis. References 1. Wang B, Xu YT, Zhang L, et al. Protoporphyrin IX fluores- cence as potential indicator of psoriasis severity and pro- gression. Photodiagnosis Photodyn Ther. 2017;19:304-307. DOI: 10.1016/j.pdpdt.2017.05.016. PMID: 28625924. 2. Xie Y, Zheng Y, Yuan M, Zhang Z, Yang C, Li J. Specific features of psoriasis vulgaris under the ultraviolet dermos- copy. Photodiagnosis Photodyn Ther. 2022;40:103100. DOI: 10.1016/j.pdpdt.2022.103100. PMID: 36055625. 3. Bissonnette R, Zeng H, McLean DI, Schreiber WE, Roscoe DL, Lui H. Psoriatic plaques exhibit red autofluorescence that is due to protoporphyrin IX. J Invest Dermatol. 1998;111(4):586-591. DOI: 10.1046/j.1523-1747.1998.00345.x. PMID: 9764837. 4. Klatte JL, van der Beek N, Kemperman PM. 100 years of Wood’s lamp revised. J Eur Acad Dermatol Venereol. 2015;29(5):842- 847. DOI: 10.1111/jdv.12860. PMID: 25428804. 5. Pietkiewicz P, Navarrete-Dechent C, Goldust M, Korecka K, Todorovska V, Errichetti E. Differentiating Fordyce Spots from Their Common Simulators Using Ultraviolet-Induced Fluorescence Dermatoscopy-Retrospective Study. Diagnostics (Basel). 2023;13(5):985. DOI: 10.3390/diagnostics13050985 . PMID: 36900129. PMCID: PMC10000991.Research Letter