Dermatology: Practical and Conceptual Original Article | Dermatol Pract Concept. 2025;15(2):5068 1 Morphological Evaluation of Facial Pigmented Lesions with Line-Field Confocal Optical Coherence Tomography: Correlation with Reflectance Confocal Microscopy. A Pilot Study Clément Lenoir1, Mariano Suppa2, Simone Soglia1, Susana Puig1, Linda Tognetti3, Elisa Cinotti3, Carmen Orte Cano2, Gwendoline Diet2, Pietro Rubegni3, Jean-Luc Perrot,4, Véronique del Marmol2, Josep Malvehy1*, Javiera Perez-Anker1* * Both senior authors equally contributed to this work. 1 Department of Dermatology, Hospital Clinic de Barcelona University of Barcelona, Universitat de Barcelona, Barcelona, Spain 2 Department of Dermatology, Hôpital Universitaire de Bruxelles, Université Libre de Bruxelles, Brussels, Belgium 3 Dermatology Unit, Department of Medical, Surgical and Neurological Sciences, University of Siena, Siena, Italy 4 Department of Dermatology, University Hospital of Saint-Etienne, Saint-Etienne, France Key words: LC-OCT, Facial Pigmented Lesions, Optical Coherence Tomography, Reflectance Confocal Microscopy, Non-Invasive Imaging Citation: Lenoir C, Suppa M, Soglia S, et al. Morphological Evaluation of Facial Pigmented Lesions with Line-Field Confocal Optical Coherence Tomography: Correlation with Reflectance Confocal Microscopy. A Pilot Study. Dermatol Pract Concept. 2025;15(2):5068. DOI: https://doi.org/10.5826/dpc.1502a5068 Accepted: February 12, 2025; Published: April 2025 Copyright: ©2025 Lenoir 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: Clément Lenoir, MD. Department of Dermatology, Hospital Clínic de Barcelona, Universitat de Barcelona, C. de Villarroel 170, 08036 Barcelona, Spain. ORCID ID: 0009-0004-5174-9932. E-mail: clement.lenoir@outlook.com Introduction: Facial pigmented lesions pose significant challenges for diagnosis and treatment plan- ning due to their anatomical topography and complexity. Traditional methods like dermoscopy have limitations, and while reflectance confocal microscopy (RCM) offers in-vivo cellular resolution, it is hindered by shallow penetration. The recently developed line-field confocal optical coherence tomog- raphy (LC-OCT) combines the benefits of OCT and RCM, providing deeper penetration and three- dimensional cellular imaging.  Objectives: This study aims to assess the ability of LC-OCT in displaying morphological features correlated and compared with RCM and histopathological findings. Methods: Over a period of 1-year, various pigmented facial lesions were selected, including solar lentigo, seborrheic keratosis, lichen planus-like keratosis, pigmented actinic keratosis, basal cell car- cinoma, compound nevus, lentigo maligna, and invasive melanoma. LC-OCT and RCM were used ABSTRACT 2 Original Article | Dermatol Pract Concept. 2025;15(2):5068 Introduction Proper management of facial skin lesions in daily derma- tology practice poses peculiar challenges due to anatomi- cal, cosmetic, diagnostic, and therapeutic considerations. Dermatologists must handle these difficulties to ensure ac- curate diagnosis and effective treatment while preserving function and achieving optimal cosmetic outcomes. Being the most continuously sun-exposed area of the human body, facial skin is a privileged localization for the development of skin cancer for which early management is paramount. Besides their own clinical expertise, dermatologists rely on auxiliary diagnostic tools such as dermoscopy, imaging, and histopathology to enhance diagnostic accuracy and guide appropriate treatment choices [1, 2]. Yet, despite all these techniques at their disposal, facial lesions remain tricky for various reasons, such as the high number of lookalikes or simulators of different biological origin and prognosis, and the difficulty of characterizing the malignancy potential of some lesions, melanocytic ones in particular. Among these developing imaging devices, reflectance confocal microscopy (RCM) is has been widely used for several years to examine the skin in vivo at a cellular resolution and its added value in patient management has already been established especially regarding pigmented lesions [3-5]. However, it allows only horizontal view of the skin, lacks penetration depth (maxi- mum 300 microns), and its interpretation requires thorough specific training and experience particularly for equivocal lesions. Line-field confocal optical coherence tomography (LC-OCT) was recently developed as an imaging technol- ogy that combines the benefits of standard OCT and RCM. It displays high resolution, 1.2-µm in axial and 1.3-µm in lateral, with 500 µm penetration depth and visualization of the vertical plane similar to histopathology. It is also the first skin imaging device able to produce tridimensional pictures of the skin with cellular resolution, allowing appreciation of micro-architectural morphology as well as cytological as- pects [6-11]. LC-OCT has been studied for its potential use in the management of various skin lesions after describing morphologic criteria and assessing diagnostic performance [12-19]. However, the added value of this technique for pig- mented facial lesions remains to be defined. Objectives The main objective of this pilot study is to describe the cor- relation between LC-OCT and RCM as well as the tridimen- sional anatomy of the most frequently encountered facial pigmented lesions in order to compare the quality of images provided by the 2 techniques and to determine if LC-OCT could potentially bring useful insight to increase diagnostic accuracy and management performance. Methods From January to June 2023, we prospectively evaluated adult patients with pigmented facial and scalp lesions and selected one case for each entity, namely solar lentigo (SL), seborrheic keratosis (SK), lichen-planus like keratosis (LPLK), pigmented actinic keratosis (AK), pigmented basal cell carcinoma (BCC), pigmented compound nevus, lentigo maligna (LM), and invasive melanoma (MM). For each case we gathered clinical and dermoscopic images with a cam- era equipped with a dermoscopic lens and polarized light (Casio). Subsequently, each lesion was examined with RCM (Vivascope 1500TM, Mavig Corp, Munich, Germany). This device integrates a dermoscopic tool which allows to navi- gate precisely in the corresponding confocal image. For each case multiple mosaic-like pictures (4x4 mm Vivablocks) were acquired at different layers of the epidermis and the dermis. Additionally, we collected images using the LC-OCT device (deepLiveTM, DAMAE Medical, Paris, France), exploring the lesion in vertical view with its videodermoscopy camera and acquired several tridimensional blocks (1,2x0,5x0,4 mm) from the regions of interest. From these tridimensional blocks we selected horizontal pictures of the examined area and correlated them with the best corresponding RCM Vivablocks showing features shared by both LC-OCT and for imaging, and their morphological features were compared. Lesions, except solar lentigo and com- pound nevus, were excised for histopathological evaluation. Morphological criteria from imaging were correlated with histopathological findings. Results: LC-OCT matched RCM in spatial resolution while providing deeper tissue penetration and three-dimensional visualization. This advantage was particularly notable in pigmented actinic kerato- sis and basal cell carcinoma, where LC-OCT’s vertical imaging offered unique diagnostic insights. It also enhanced the understanding of the architecture of melanocytic lesions. Conclusion: LC-OCT adds new insight into the imaging and diagnosis of facial pigmented lesions, of- fering additional morphological features. This pilot study highlights its potential to improve diagnostic accuracy and patient care, with further research needed to assess its broader clinical applications. Original Article | Dermatol Pract Concept. 2025;15(2):5068 3 RCM. The analysis of horizontal LC-OCT acquisitions was based on criteria and morphologic features already described and established in RCM and LC-OCT literature. Moreover, except for the SL, SK and pigmented compound nevus, which were without doubt benign either clinically, derma- toscopically and/or after imaging examination, all other le- sions were either biopsied or excised for diagnostic as well as therapeutic purpose. In these cases, we also selected the best matching correlation between the features seen in LC- OCT vertical view and the histopathological equivalent, also based on morphologic criteria well-established in the pathol- ogy literature. No horizontal histopathological section was performed due to the sample processing that would impair the diagnostic and prognostic assessment which is crucial es- pecially in equivocal melanocytic tumors. Results Solar Lentigo Horizontal mode of LC-OCT displays the same typical fea- tures of SL that have been described in RCM examination i.e. a regular honeycomb pattern and intertwined dermal papil- lae with elongated cord-like rete ridges corresponding to the lentiginous pigmented keratinocyte proliferation, preserv- ing follicular integrity [3, 4, 20]. It is the same pattern that translates into the typically regular pigment network with fingerprint-like areas in dermoscopy [1]. Nuclei of keratino- cytes are more clearly identified in LC-OCT than in RCM as regular roundish dark shapes inside the cells, although the granular melanin pigmentation appears more finely con- trasted in RCM. The vertical view combined with tridimen- sional display in LC-OCT allows the clinician to appreciate the architecture of SL with more histopathological-like and real-life perspective. The cord-like rete ridges are distributed in a regular fashion in the papillary dermis and the keratino- cytes are monomorphous and evenly pigmented at the basal layer, without hyperkeratosis nor acanthosis (Figure 1). Seborrheic Keratosis SK belongs to the same spectrum of lesion as SL, sometimes arising from one, and as such it shares common morpholog- ical features with SL in RCM [20] and LC-OCT. Epidermal architecture remains regular and shows a typical honeycomb pattern with coiled dermal papillae and thickened cord-like rete ridges. In the left part of these acquisitions, which fo- cuses on a more acanthotic and keratotic area of the SK, we can observe hyperreflective horn cysts filled with keratin. LC-OCT signal penetrates deeper in the lesion and reaches the lower ridge of the horn cyst observed on tridimensional reconstruction. This view also forthrightly emphasizes the Figure 1. LC-OCT imaging and corresponding RCM features of solar lentigo (SL). (A) Dermoscopic and (B) RCM Vivablock overviews; (C) matching horizontal LC-OCT and (D) RCM (D) views; and (E) vertical histology-like and (F) tridimensional LC-OCT views. Intertwined dermal papillae and elongated rete ridges (yellow arrows) are visible in all the acquisitions and indicate lentiginous keratinocytic prolifer- ation, preserving follicular integrity (green stars). Horizontal LC-OCT view shows a regular honeycomb pattern similar to RCM. Nuclei of keratinocytes appear as roundish dark shapes more clearly in LC-OCT than in RCM (red arrows) while melanin pigment is more finely defined in RCM. 4 Original Article | Dermatol Pract Concept. 2025;15(2):5068 Pigmented Actinic Keratosis Pigmented AK, mostly found on the face and scalp, is one of the several described subtypes of AK, though it is the only one that can be confused with an atypical melanocytic lesion and hence the most crucial to accurately diagnose. The main feature observed upon horizontal view of LC-OCT just like in RCM is pigmented keratinocytic pleomorphism, known as atypical honeycomb pattern. Although RCM brings finer brightness contrast related to the degree of melanic pigmen- tation as well as better-defined interkeratinocytic cell junc- tions, LC-OCT shows highly defined nuclei corresponding to the black roundish and oval shapes inside the keratinocytes. Moreover, keratinocytic pleomorphism is more precisely as- sessed in vertical and tridimensional view of LC-OCT thanks to the projection of the whole epidermal thickness on one scan. We can easily appreciate the degree and topography of atypia with nuclei of irregular shape and size compared to the previously described SL, mostly noticeable in the lower half of the epidermis in this case, which is diagnostic of low- grade AK. The enlarged atypical keratinocytes of the basal regularity and homogenous distribution of the epidermal projections. (Figure 2). Lichen Planus-Like Keratosis LPLK arises from SL or SK, and as such they all share com- mon features in dermoscopy, histopathology and in vivo skin imaging. The regular honeycomb pattern is largely preserved and the same cord-like rete ridges that we see in SL and SK are observed in both LC-OCT and RCM as described before. Vertical view of LC-OCT provides additional features such as the bright horizontal line just underneath the dermoepi- dermal junction (DEJ), underlining a large band of marked elastosis as seen in histopathology. Furthermore, we can best appreciate the focal loss of sharp demarcation between the epidermis and the dermis in vertical histology-like display of LC-OCT, which reflects the lichenoid interface inflam- mation that contains multiple bright plump cells and bright dots scattered throughout the dermis corresponding to mela- nophages and lymphocytes. These are observed with greater depth penetration than in RCM (Figure 3). Figure 2. LC-OCT imaging and corresponding RCM features of seborrheic keratosis (SK). (A) Dermoscopic and (B) RCM Vivablock over- views; (C) matching horizontal LC-OCT and (D) RCM views; and (E) vertical histology-like and (F) tridimensional LC-OCT views. Regular honeycomb pattern coiled dermal papillae and thickened cord-like rete ridges with lentiginous keratinocytic proliferation (yellow arrows) are seen in all acquisitions. The left part of the lesion shows a hyperreflective horn cyst filled with keratin (purple stars), wholly and clearly observed in LC-OCT. Original Article | Dermatol Pract Concept. 2025;15(2):5068 5 Figure 3. LC-OCT imaging, corresponding RCM features, and histopathology of lichen planus-like keratosis (LPLK). (A) Dermoscopic and (B) RCM Vivablock overviews; (C) matching horizontal LC-OCT and (D) RCM views; and (E) vertical LC-OCT, (F) histopathology and (G) tridimensional LC-OCT views. Focal loss of sharp demarcation between epidermis and dermis is visible in LC-OCT and RCM with vertical view of LC-OCT providing a more histology-like perspective. It corresponds to lichenoid interface inflammation (orange stars), with plump cells and bright dots representing melanophages (blue arrows) as well as lymphocytes scattered throughout the dermis, more deeply observed than in RCM. The vertical view of LC-OCT highlights a bright horizontal line just beneath the DEJ, indicating marked elastosis as confirmed in histopathology. Follicles (green stars) are preserved. layer focally appear pigmented, but do not dive into the fol- licles, and there are no dendritic and pagetoid bright cells in the upper layers of the epidermis. Underneath the flattened DEJ, we can observe the same fine bright horizontal line that we saw in the LPLK covering a homogenous grayish papil- lary dermis that displays marked elastosis in histopathology (Figure 4). Pigmented BCC The pigmented variant of BCC, more commonly found on the face and scalp area, shares most of its features with all the other subtypes of BCCs in RCM and LC-OCT, in ad- dition to some more specific signs that we can observe in this case. The lobules appear as cohesive cord-like structures, containing several plump bright oval-shaped elements, cor- responding to melanophages, pigmented melanocytes and Langerhans cells. Vertical as well as tridimensional display in LC-OCT is highly superposable with histology and we can ef- fortlessly observe the tumor lobules, of which the connection to the epidermis appears more obvious than in RCM. The deep tumor borders also emerge as much better-defined in LC-OCT, with a clear picture of clefting revealed underneath the lobules, echoing the well-established eponym histological feature (Figure 5). Pigmented Compound Naevus Melanocytic nevi of the face present as variably pigmented lesions depending on the depth and pigmentation degree of melanocytic proliferation. The typically described ring- pattern as observed in RCM and LC-OCT horizontal view of LC-OCT of pigmented nevi is not strikingly observed in this compound nevus on the cheek of a young patient due to the physiological flattening of the DEJ in facial skin. However, we can observe several monomorphous bright structures surrounding small papillae, forming nests corre- sponding to benign melanocytes. These are visible mainly along the DEJ in both RCM and LC-OCT, but the combina- tion of vertical view and tridimensional display in LC-OCT 6 Original Article | Dermatol Pract Concept. 2025;15(2):5068 Figure 4. LC-OCT imaging, corresponding RCM features, and histopathology of pigmented actinic keratosis (AK). (A) Dermoscopic and (B) RCM Vivablock overviews; (C) matching horizontal LC-OCT and (D) RCM views; and (E) vertical LC-OCT, (F) histopathology, and (G) tridimensional LC-OCT views. Horizontal views of both RCM and LC-OCT display an atypical honeycomb pattern corresponding to pigmented keratinocytic pleomorphism (blue arrows). Vertical view of LC-OCT clearly confirms the basal localization of this atypical prolif- eration. While visible in both techniques, features such as nuclear shape and pleomorphism are more easily observed in LC-OCT as irregular black oval structures, while cellular shape and pleomorphism, interkeratinocytic cell junctions as well as melanin pigment are more finely contrasted in RCM. The flattened DEJ, best observed in vertical view of LC-OCT, underlines a fine bright horizontal line indicative of marked elastosis (orange stars) as confirmed in histopathology. facilitates the understanding of the global architecture, here well- preserved, in terms of size, shape, location and distribu- tion of the melanocytic proliferation. Moreover, the absence of large, bright, roundish and dendritic cells emphasizes the benign character of the lesion (Figure 6). Lentigo Maligna LM is the most common subtype of melanoma on the face and scalp and RCM has already been proven significantly valuable for its diagnosis and surgical treatment planning. Horizontal view of LC-OCT can display just like RCM the most prominent diagnostic criterion of LM which is the presence of atypical melanocytes in the shape of large and pleomorphic bright cells. They appear as large roundish cells with abundant cytoplasm and can project numerous dendrites visible in the epidermis, with better vertical res- olution in LC-OCT than in RCM. Those melanocytes are seen proliferating in a contiguous manner along the basal membrane, diving inside the follicles as well as spreading to the upper layers of the epidermis in a pagetoid fashion. The straightforward visualization of the DEJ in vertical view or tridimensional setting of LC-OCT allows to evaluate the in- tegrity of the basal membrane throughout the whole lesion as seen in this in situ melanoma (Figure 7). Superficial Spreading Melanoma Invasive melanomas of the face and scalp share most of their morphological features with the in situ counterparts from which they develop over time. The same large pleo- morphic roundish and dendritic bright cells are observed in both RCM and LC-OCT. They are numerous, isolated or grouped in nests of variable size along the junction and in the epidermis, including the follicles. The DEJ, best as- sessed in vertical view and tridimensional reconstruction of LC-OCT, appears blurry and correlates with the histo- logical picture of breached basal membrane, signing the invasive aspect of the lesion. Moreover, disarrangement of both the honeycomb and meshwork patterns underlines the consumption of the epidermis and its altered architecture. (Figure 8). Original Article | Dermatol Pract Concept. 2025;15(2):5068 7 histological subtype of these lesions with more ease and pre- cision than in the sole horizontal view provided by RCM. In the case of AK, besides allowing to grade the degree of atypia in the different epidermal layers as is done routinely in histopathology, this can be typically useful to detect in vivo the proliferative subtype of AK (pigmented or not), which is known to be the most aggressive and at risk of developing into SCC. Same goes regarding BCC where the distinction between indolent and aggressive subtypes has already been proven significantly efficient in LC-OCT, allowing better treatment planning, much appreciated in an area as essential as the face. In the case of melanocytic pigmented lesions of the face where assessment of global architecture and distri- bution of the melanocytic proliferation is paramount in the diagnostic process, LC-OCT also brings valuable additional information. Though RCM can already display the overall horizontal architecture of the lesion, LC-OCT shows with more clarity the location and the connection of melanocytic cells and nests with the epidermis, the follicles, the basal membrane and the dermis, allowing better assessment of the tridimensional architecture. Moreover, thanks to the vertical Discussion Morphologic features and diagnostic criteria for most skin lesions have been extensively described in histopathology which remains the gold-standard to this day. More recently, RCM offered a high-resolution horizontal perspective, and a new range of descriptive patterns and criteria were pub- lished over the years to help dermatologists achieve a more precise in vivo characterization of suspicious lesions. Finally, LC-OCT was developed with the aim of combining the ben- efits of RCM in terms of spatial resolution with the deeper signal penetration and the vertical imaging of conventional OCT. As such, it is the first skin imaging technology able to provide in vivo histology-like pictures of skin lesions with cellular resolution. With adequate training the dermatologist can therefore be expected to recognize features described in both RCM and histopathology when examining a skin lesion with LC-OCT. This proves especially helpful in lesions such as AK and BCC where vertical and tridimensional imaging provide the most clear-cut and straightforward diagnostic criteria. Moreover, LC-OCT can potentially help specify the Figure 5. LC-OCT imaging, corresponding RCM features, and histopathology of pigmented basal cell carcinoma (BCC). (A) Dermoscopic and (B) RCM Vivablock overviews; (C) matching horizontal LC-OCT and (D) RCM views; and (E) vertical LC-OCT, (F) histopathology, and (G) tridimensional LC-OCT views. Both RCM and LC-OCT demonstrate lobular structures typical of BCC (orange stars), containing plump bright oval-shaped elements, identified as melanophages, pigmented melanocytes, and Langerhans cells (purple arrows). Vertical and tridimensional LC-OCT views closely mirror histological findings, depicting the tumor lobules, the clefting visible beneath them and their connection to the epidermis, in a more intuitive manner than in the horizontal view of RCM for the pathology-trained eye. 8 Original Article | Dermatol Pract Concept. 2025;15(2):5068 which are prominent mostly in atypical melanocytic lesions, both techniques display them efficiently, with finer contrast in RCM but better vertical resolution in LC-OCT where the dendrites can easily be followed from one horizontal plane to the next. Limitations As for the limitations of the study, it should be reminded that the findings resulting from those correlations were obtained based on the analysis of a single lesion for each type of di- agnosis. Except for SL, each lesion was selected after being deemed clinically equivocal and for which the in vivo ex- amination showed the clearest features as previously estab- lished in LC-OCT, RCM and histopathology literature. It is therefore possible that some of these diagnoses may present with varying morphological features that were not exhaus- tively described in this study. For example, regarding BCC, the infiltrative subtype is known to be the most difficult to display and deeper penetration of LC-OCT compared to RCM, the papillary dermis becomes more accessible for in vivo analysis and can reveal additional relevant features. The bright horizontal line particularly well visible in LPLK and pigmented AK just underneath the epidermis seems to cor- relate with marked elastosis in histopathology, probably due to an increased difference of signal absorption and reflection than in normal skin between the epidermis and he dermis. In- flammatory cells in the form of plump bright cells and small bright dots are also effortlessly observed, particularly in the LPLK where they are numerous. In terms of spatial resolu- tion, LC-OCT appears to provide similar performances to RCM but with subtle differences in the projected structures. Cell nuclei are more clearly visible in LC-OCT than in RCM images: in particular, LC-OCT allows an easy appreciation of the degree of nuclear pleomorphism, especially in AK or LM cases. Of converse, the melanin pigment and the inter- keratinocytic cellular junctions appear with more contrast in RCM than in LC-OCT. Regarding large dendritic cells Figure 6. LC-OCT imaging and corresponding RCM features of a pigmented compound nevus. (A) Dermoscopic and (B) RCM Vivablock overviews; (C) matching horizontal LC-OCT and (D) RCM views; and (E) vertical and (F) tridimensional LC-OCT views. Both RCM and LC-OCT horizontal views reveal monomorphous bright structures forming nests of benign melanocytes around small papillae (yellow stars), predominantly along the DEJ. The vertical and tridimensional LC-OCT views provide a clearer understanding of the lesion's architecture, showing well-preserved global structure in terms of size, shape, location, and distribution of the melanocytic proliferation. Green stars indi- cate follicles, which are preserved. Original Article | Dermatol Pract Concept. 2025;15(2):5068 9 Figure 7. LC-OCT imaging and corresponding RCM features of lentigo maligna (LM). (A) Dermoscopic and (B) RCM Vivablock overviews; (C) matching horizontal LC-OCT and (D) RCM views; and (E) vertical LC-OCT, (F) histopathology, and (G) tridimensional LC-OCT views. Horizontal views of both RCM and LC-OCT highlight the presence of confluent atypical melanocytes (red arrows) reaching the follicle nearby. These melanocytes proliferate along the basal membrane as clearly observed in vertical view of LC-OCT. Some are seen in the upper layers of the epidermis (blue arrows). Vertical and tridimensional LC-OCT views enable clear visualization of the DEJ and assessment of basal membrane integrity in this in situ lesion. diagnose in dermoscopy as well as in skin imaging, and a skin biopsy is usually necessary to confirm the suspected di- agnosis. However, the main features described in each lesion are expected to be observed in most cases routinely seen in dermatology consultation and their relevance was certainly also shaped by our own real-life experience as skin imaging consultants. It is evident that further studies are needed to evaluate each sign’s value in terms of sensibility and specific- ity as diagnostic criteria, as has been done for other diagnos- tic technologies in the past. Conclusions With LC-OCT being a recent technology, continuously devel- oping and adapting tools to aid the dermatologist in achiev- ing better in vivo diagnostic performance, we can expect it to fulfill some yet unmet needs particularly in the difficult field of pigmented facial lesions. This first-of-its-kind pilot study comparing superposable pictures of LC-OCT and RCM of the most common pigmented facial lesions is a first step in determining the added value of this new technology. Its ability to project horizontal pictures with similar spatial resolution to RCM as well as to display histology-like and tridimensional view of skin lesions allows to integrate the previously described and well-established morphological cri- teria from both RCM and histopathology for each lesion. Moreover, the ongoing development of artificial intelligence as well as algorithms that provide a clear assessment of key structures like the DEJ and the microvascular environment may lead to a better understanding of how these lesions de- velop in facial skin. Finally, LC-OCT could represent a major step closer to the ideal of a technology that would one day be able to provide a full tridimensional in vivo reconstruction of a whole lesion. 10 Original Article | Dermatol Pract Concept. 2025;15(2):5068 of skin tumors. J Biomed Opt. 2018;23(10):1-9. DOI:10.1117/1. JBO.23.10.106007. PMID: 37278496. 7. Monnier J, Tognetti L, Miyamoto M, et al. 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