Dermatology: Practical and Conceptual Image Letter | Dermatol Pract Concept. 2024;14(3):e2024144 1 UV Dermoscopy as a Diagnostic Tool to Differentiate Between Pediculosis and Piedra Branca Bianca Spina Papaleo1, Gustavo de Sá Menezes Carvalho2, Guilherme Camargo Julio Valinoto3, John Verrinder Veasey3 1 Dermatology resident at the Irmandade da Santa Casa de Misericórdia de São Paulo (ISCMSP) - São Paulo (SP), Brasil 2 Dermatologist at AC Camargo Cancer Center, São Paulo (SP), Brasil 3 Dermatologist at Irmandade da Santa Casa de Misericórdia de São Paulo (ISCMSP) - São Paulo (SP), Brasil Citation: Spina Papaleo B, de Sá Menezes Carvalho G, Camargo Julio Valinoto G, Verrinder Veasey J. UV Dermoscopy as a Diagnostic Tool to Differentiate Between Pediculosis and Piedra Branca. Dermatol Pract Concept. 2024;14(3):e2024144. DOI: https://doi.org/10.5826/ dpc.1403a144 Accepted: January 23, 2024; Published: July 2024 Copyright: ©2024 Spina Papaleo 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: Bianca Spina Papaleo, Irmandade da Santa Casa de Misericórdia de São Paulo (ISCMSP) 112, Dr Cesario Mota Junior Street, São Paulo / State: São Paulo. Zip-Code: 01221-020. Tel: 11-21767000 Email: biancapapaleo@me.com Case Presentation A 4-year-old girl presented with a 3-month history of white nodules on hair, most evident on wet hair. There was no as- sociated pruritus. The patient was being treated with per- methrin 1% solution, without success. Examination with polarized dermoscopy revealed clear and soft white nodules on the hair shaft, and direct observation made the diagnosis of white piedra. UV induced fluorescence dermoscopy made the nodules more evident, in what we called a “constella- tion pattern” (Figure 1A). On the same week, a 6-year-old girl presented with a month history of pruritus and white nodules on hair. Dermoscopy showed similar white nodules on the hair shaft, but UV Dermoscopy showed a different presentation: a tulip pattern, which showed nits adhering to the hair through its glue, making the diagnosis of pediculosis more accurate (Figure 2a). Teaching Point White piedra is a hair mycosis, presenting as white nodules on the hair [1], treated with ketoconazole. Pediculosis is a parasitic infection of the scalp, presenting with intense itching and the presence of nits, which adhere to the hair through a sheath made of aminoacids [2], and it is treated with permethrin. Clinically, they are sometimes indistin- guishable, and although trichoscopy can help, it can also be similar [2]. UV dermoscopy, on the other hand, allows for accurate diagnosis evidencing what we call a constel- lation pattern in piedra branca and a tulip pattern in pe- diculosis, which can be very useful for clinical diagnosis when direct examination through optical microscopy is not available. 2 Image Letter | Dermatol Pract Concept. 2024;14(3):e2024144 References 1. Burkhart CN, Burkhart CG. Head lice: scientific assessment of the nit sheath with clinical ramifications and therapeutic op- tions. J Am Acad Dermatol. 2005;53(1):129-133. DOI: 10.1016 /j.jaad.2005.01.134. PMID: 15965432. Figure 1. (A) UV dermoscopy revealing clear and soft white nodules on the hair shaft (Dermlite DL5 paired with iPhone - 20x zoom). (B) Polarized trichoscopy of piedra branca, with the same white nod- ules (10x zoom). Figure 2. (A) UV dermoscopy of pediculosis, showing a tulip pat- tern and making the pediculosis glue more visible (20x zoom). (B) Polarized trichoscopy of pediculosis, very similar to piedra branca dermoscopy, showing white nodules on the hair shaft (Dermlite DL5 paired with iPhone - 40x zoom) 2. Lacarrubba F, Verzì AE, Micali G. Trichoscopy in the Differen- tial Diagnosis of Pseudonits. Skin Appendage Disord. 2019;5(3): 142-145. DOI: 10.1159/000493741. PMID: 31049334. PMCID: PMC6489062.