Dermatology: Practical and Conceptual Image Letter | Dermatol Pract Concept. 2024;14(4):e2024273 1 Sub-Ultraviolet Light Dermatoscopy for Surgical Margin Definition in Lentigo Maligna Melanoma Itziar Muelas Rives¹, Laura Bernal Masferrer¹, Beatriz Clemente Hernández¹, Leticia Ollero Domenche², Maria Carmen Gómez Mateo², Marcial Álvarez Salafranca¹ 1 Dermatology Service, Miguel Servet University Hospital, IIS Aragón, Zaragoza, Spain 2 Pathology Service, Miguel Servet University Hospital, Zaragoza, Spain Citation: Muelas Rives I, Bernal Masferrer L, Clemente Hernández B, Ollero Domenche L, Gómez Mateo MC, Álvarez Salafranca M. Sub-Ultraviolet Light Dermatoscopy for Surgical Margin Definition in Lentigo Maligna Melanoma. Dermatol Pract Concept. 2024;14(4):e2024273. DOI: https://doi.org/10.5826/dpc.1404a273 Accepted: July 2, 2024; Published: October 2024 Copyright: ©2024 Muelas Rives 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: Dr. Itziar Muelas Rives. Dermatology Service. Miguel Servet University Hospital. Paseo Isabel la Católica 1-3. CP: 50009 – Zaragoza (Spain). E-mail: itziar.muelas.rives@gmail.com Case Presentation A 62-year-old man presented with a progressively enlarging pigmented lesion on the scalp for over five years. Physical ex- amination revealed an intensely pigmented patch, 8 x 5 mm in diameter, surrounded by severe photodamage with mul- tiple solar lentigines and field cancerization (Figure 1A). Polarized light dermatoscopic examination showed an atypi- cal pseudonetwork, rhomboids, structureless blue pigmenta- tion, and streaks. Additionally, there was a subtle peripheral light brown pigmentation, clinically similar to other solar lentigines on the scalp, in which some “isobar” (circle within a circle) structures were visible (Figure 1B). Using 405-nm light dermatoscopy (dermatoscope DZ-D100, Casio Computer Co, Ltd, Tokyo, Japan), we were able to better define the true extension of the lesion (Figure 1C). Histopathological examination of the com- plete excision of both components revealed a 18 x 5 mm in diameter, non-ulcerated lentigo maligna melanoma (LMM), with a Breslow thickness of 0.5 mm (Figure 1D-E). Teaching Point The definition of surgical margins in lentigo maligna/LMM can be challenging due to its frequent subclinical exten- sion and poor peripheral demarcation. Dermatoscopy with 405 nm sub-ultraviolet (UV) light can help to better define these margins in comparison with naked eye examination or conventional polarized dermatoscopy [1,2]. The 405 nm sub-UV light highlights melanin distribution in a dark gray color due to its higher absorption by melanin. Furthermore, this technique has shown to enhance the observation of some dermatoscopic criteria in comparison with conventional der- matoscopy, such as ulceration, crusts, comedo-like openings, milia-like cysts, multiple aggregated yellow globules, and fissures and ridges [1,2]. 2 Image Letter | Dermatol Pract Concept. 2024;14(4):e2024273 References 1. Pietkiewicz P, Navarrete-Dechent C, Togawa Y, et al. Applica- tions of Ultraviolet and Sub-ultraviolet Dermatoscopy in Neo- plastic and Non-neoplastic Dermatoses: A Systematic Review. Dermatol Ther (Heidelb). 2024;14(2):361-390. doi: 10.1007 /s13555-024-01104-4. 2. Minagawa A, Meling MT, Koga H, Okuyama R. Near-ultraviolet Light Dermoscopy for Identification of Pigmented Skin Tumours. Acta Derm Venereol. 2023;103:adv00876. doi: 10.2340/actadv .v103.5302. Figure 1. (A) Intensely pigmented lesion located on the scalp surrounded by severe photodamage and field cancerization. (B) Polarized light dermatoscopy showed an atypical pseudonetwork, rhomboids, structureless blue pigmentation, and streaks. Moreover, cir- cle within a circle structures, also called “isobars”, were present in the subtly pigmented periphery of the lesion. (C) Sub-UV dermatoscopy showed a more precise delimitation of the lesion beyond the clinically and dermatoscopically evident margins. (D) Proliferation of single and nested atypical melanocytes along the basal epidermis, with an invasive compo- nent and involvement of adnexal epithelium (H&E, x4). (E) At higher magnification, cyto- logic atypia, follicular involvement, and pagetoid spread were clearly visible (H&E, x10).