Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2025;15(3):5344 1 Enhancing Diagnosis of Flat Pigmented Basal Cell Carcinoma with Line-Field Confocal Optical Coherence Tomography Antonio Di Guardo1,2, Luca Ambrosio1,2, Giovanni Di Lella2, Giovanni Pellacani1, Claudio Conforti2,3 1 Department of Clinical Internal, Anesthesiological and Cardiovascular Sciences, “Sapienza” University of Rome, Rome, Italy 2 IDI-IRCCS, Dermatological Research Hospital, Rome, Italy 3 Link University of Rome, Italy, Department of Life Science, Health, and Health Profession Key words: Line-field confocal optical coherence tomography, Basal cell carcinoma, Dermoscopy, Reflectance confocal microscopy, Dermatological diagnostics Citation: Di Guardo A, Ambrosio L, Di Lella G, Pellacani G, Conforti C. Line-field confocal optical coherence tomography, Basal cell carcinoma, Dermoscopy, Reflectance confocal microscopy, Dermatological diagnostics. Dermatol Pract Concept. 2025;15(3):5344. DOI: https://doi.org/10.5826/dpc.1503a5344 Accepted: February 20, 2025; Published: July 2025 Copyright: ©2025 Di Guardo 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: Luca Ambrosio, MD, Department of Clinical Internal, Anesthesiological and Cardiovascular Sciences, “Sapienza” University of Rome, Rome, Italy. IDI-IRCCS, Dermatological Research Hospital, 00167 Rome, Italy. E-mail: luca.ambrosio@uniroma1.it Introduction Line-field confocal optical coherence tomography (LC-OCT) is a novel, noninvasive imaging modality that merges the depth resolution of optical coherence tomography with the cellular detail of reflectance confocal microscopy [1,2]. By providing real-time, high-resolution, en face and cross- sectional images of the skin, LC-OCT has enhanced the in vivo diagnostic evaluation of numerous dermatologic condi- tions, including both benign and malignant tumors [3]. We report a rare and diagnostically challenging case of basal cell carcinoma (BCC) presenting as a pigmented macule in which LC-OCT played a pivotal in establishing the diagnosis. Case Presentation An 84-year-old male presented with a pigmented lesion on the dorsum of his nose, present for approximately two years and progressively darkening. The lesion was asymptomatic and had not undergone any significant changes in size or texture. The patient had no history of skin cancer or chronic sun exposure. Clinically, the lesion appeared as a flat, pig- mented macule measuring 7 mm in diameter, with irregular yet sharply demarcated borders. Differential diagnoses in- cluded lentigo maligna, solar lentigo, and pigmented actinic keratosis. Dermoscopy revealed rhomboidal structures, an annular granular pattern, white circles around a keratotic 2 Research Letter | Dermatol Pract Concept. 2025;15(3):5344 plug and a solitary pigmented globule at the inferior edge. These findings suggested a malignant process but were not diagnostic. LC-OCT (Damae Medical, Paris, France) imaging was performed. En face and vertical images revealed sharply demarcated dermal lobules surrounded by a dark hypore- flective rim, consistent with the “clefting” pattern typical of BCC. These lobules were encased by an outer hyperreflective “bright rim,” while the central portions displayed a mille- feuille pattern, indicating dense basaloid cell proliferation [4]. The homogeneous distribution of findings  throughout the lesion, excluded a focal process. Based on these features, an excisional biopsy was performed and histology confirmed the diagnosis of pigmented BCC (Figure 1). Conclusion Pigmented BCCs presenting as macules, can closely mimic melanocytic lesions, both clinically and dermoscopically. As highlighted by Navarrete-Dechent et al., such lesions may show angulated or rhomboidal lines on dermoscopy, typi- cally associated with lentigo maligna [5]. In this setting, LC- OCT provides high-resolution architectural and cytologic detail that facilitates noninvasive identification of hallmark BCC features, including lobular arrangements, peripheral clefting, and characteristic reflectivity profiles [1]. In our case, LC-OCT allowed confident pre-biopsy identification of BCC, supporting a timely excisional ap- proach and guiding therapeutic planning. The integration of dermoscopy and LC-OCT may significantly enhance diagnostic accuracy for atypical lesions, reduce unneces- sary biopsies, and streamline clinical decision-making. As LC-OCT becomes more accessible in clinical practice, its role as a “virtual histology” tool is likely to expand, offer- ing substantial benefit in evaluating equivocal or high-risk lesions. References 1. Latriglia F, Ogien J, Tavernier C, et al. Line-Field Confocal Optical Coherence Tomography (LC-OCT) for Skin Imaging in Dermatology.  Life (Basel). 2023;13(12):2268. Published 2023 Nov 28. DOI:10.3390/life13122268; 2. Ogien J, Tavernier C, Fischman S, Dubois A. Line-field confo- cal optical coherence tomography (LC-OCT): principles and practical use.  Ital J Dermatol Venerol. 2023;158(3):171-179. DOI:10.23736/S2784-8671.23.07613-2; 3. Suppa M, Palmisano G, Tognetti L, et al. Line-field confocal op- tical coherence tomography in melanocytic and non-melanocytic skin tumors.  Ital J Dermatol Venerol. 2023;158(3):180-189. DOI:10.23736/S2784-8671.23.07639-9; 4. Suppa M, Fontaine M, Dejonckheere G, et al. Line-field con- focal optical coherence tomography of basal cell carcinoma: a descriptive study.  J Eur Acad Dermatol Venereol. 2021;35(5): 1099-1110. DOI:10.1111/jdv.17078; 5. Navarrete-Dechent C, Uribe P, Rabinovitz H, Abarzua-Araya A, Kittler H. Basal Cell Carcinomas Presenting as Flat Pigmented Macules on the Face Mimicking Lentigo Maligna on Dermoscopy: A Case Series. Dermatol Pract Concept. 2023;13(1):e2023038. Published 2023 Jan 1. DOI:10.5826/dpc.1301a38. Figure 1. (A) 84-year-old mle with a flat, pigmented macule measuring approximately 7 mm in diameter. (B) Der- moscopy under polarized mode showed rhomboidal structures and an annular granular pattern, along with white circles surrounding a keratotic plug and a solitary pigmented globule at the lower pole of the lesion. (C) LC-OCT examination revealed dermal lobules (dashed purple lines), clefting (purple arrow), bright rims (yellow arrow), a thinned epidermis (blue brace), and a millefeuille pattern within the lobules (white asterisks). (D) The 3D recon- struction allows for a clear visualization of the dermal lobules, corresponding to basaloid islands.