Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2024;14(4):e2024261 1 Optical Super-High Magnification Dermoscopy in the Diagnosis of Equivocal Melanocytic Lesions: Poor Agreement on Current Terminology and Future Perspectives Stefania Guida1,2, Shaniko Kaleci3, Renato Rossi4, Giulia Radi5, Elisa Molinelli6, Giovanni Pellacani7, Elisa Cinotti8, Italian Optical Super-High Magnification Dermoscopy Group# 1 School of Medicine, Vita-Salute San Raffaele University, Milan, Italy 2 Dermatology Clinic, IRCCS San Raffaele Scientific Institute, Milan, Italy 3 Dermatology Unit, Surgical, Medical and Dental Department of Morphological Sciences Related to Transplant, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy 4 Department of Dermatology, Skin Center Senigallia, Ancona, Italy 5 Azienda Sanitaria Territoriale Pesaro-Urbino, Pesaro, Italy 6 Dermatological Clinic Department of Clinical and Molecular Sciences, Polytechnic University of the Marche Region, Ancona, Italy 7 Dermatology Clinic, Department of Clinical Internal, Anesthesiological and Cardiovascular Sciences, Sapienza University of Rome, Rome, Italy 8 Dermatology Section, Department of Medical, Surgical, and Neurological Sciences, Santa Maria Alle Scotte Hospital, Siena, Italy #Membrs Italian Optical Super-High Magnification Dermoscopy Group are listed in the Appendix A Key words: Super-high magnification dermoscopy, Dermoscopy, Diagnostic accuracy, Terminology, Agreement Citation: Guida S, Kaleci S, Rossi R, et al. Optical Super-High Magnification Dermoscopy in the Diagnosis of Equivocal Melanocytic Lesions: Poor Agreement on Current Terminology and Future Perspectives. Dermatol Pract Concept. 2024;14(4):e2024261. DOI: https://doi.org/10.5826/dpc.1404a261 Accepted: July 3, 2024; Published: October 2024 Copyright: ©2024 Guida 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: Stefania Guida, Vita-Salute San Raffaele University, Via Olgettina 58, 20132 Milan, Italy. E-mail: guida.stefania@hsr.it Introduction Optical super-high magnification dermoscopy (OSHMD) represents a new advancement in dermoscopy which en- ables up to 400x magnification, allowing the visualization of structures commonly not observable with 20x conventional dermoscopy [1,2]. OSHMD has been used in the differential diagnosis be- tween nevi and melanomas, highlighting some discriminat- ing criteria, including cell irregularity in shape and size [1,2]. Despite the mounting interest concerning this technique, data are still scarce. This paper aimed to describe our experience in a cohort of patients with dermoscopically equivocal melanocytic 2 Research Letter | Dermatol Pract Concept. 2024;14(4):e2024261 lesions and to present the previously unreported agreement on OSHMD criteria between different evaluators. Case Presentation Flat dermoscopically equivocal pigmented lesions, diag- nosed as either nevi or melanoma, were retrospectively an- alyzed. The diagnosis was confirmed by histopathological examination or by a 2-year follow-up. Data regarding age, sex, and anatomic location were also retrieved. Acral lesions were excluded. OSHMD images of all cases were collected and assessed according to previously described criteria [1,2]. Evaluations, blinded to histopathologic diagnosis, were performed by three evaluators, experts in dermoscopy and trained in OSHMD. The first and the third evaluators had >5 years of experience with OSHMD, and the second evaluator had <5 years of experience with OSHMD. The first evaluator also had >10 years of experience with reflectance confocal microscopy (RCM). Statistical evaluation was carried out with the STATA software version 17 (StataCorp 2021; Stata Statistical Soft- ware: Release 17, StataCorp LLC). Cohen’s Kappa was employed to estimate the agreement among evaluators for the recognition of features. Values below 0.2 indicate poor agreement, between 0.21 and 0.40 fair agreement, 0.41-0.60 moderate agreement, 0.61 - 0.80 substantial agreement, and 0.81 - 1.00 indicate almost perfect agreement. A total of 74 nevi and 20 melanomas, mostly located on the trunk and limbs, were included. The mean age was 47.8±16.4 (range 8-93), with 53% females. The mean Breslow thickness was 0.12 (range 0–0.6). Data revealed substantial agreement between all eval- uators for vessels only (Figure 1A). Fair agreement was observed for cell irregularity and some aspects of network characteristics (Figures 1B,C). Poor-to-moderate agreement was observed for all other parameters, with heterogeneous results between different evaluators (Table 1). Conclusions In the current study, the best agreement between the three evaluators was found for vessels, cell irregularities, and network with edged papillae, which are likely the easiest parameters to be identified under OSHMD. On the other hand, overall poor agreement on the identification of other OSHMD features was observed. A potential pitfall may be related to OSHMD terminology, showing some similarities with RCM and conventional dermoscopy features. This sim- ilarity can be misleading for evaluators with experience with different imaging tools. Other potential limitations may be related to the retro- spective nature of the study, the inclusion of difficult differen- tial diagnoses of clinically atypical nevi and thin melanomas, and the lack of guidelines for acquiring images enabling the proper identification of OSHMD features. Taken together, these results show that further efforts should be made for the development of a terminology shared between experts to improve the recognition of OSHMD features. Table 1. Intraclass Correlation Coefficient According to OSHMD Features. OSHMD features k-value 1 vs 2 % of agreement 1 vs 2 k-value 1 vs 3 % of agreement 1 vs 3 k-value 2 vs 3 % of agreement 2 vs 3 Keratinocyte 0.086 72.3 0.157* 67 0.464** 64.9 Roundish melanocytes 0.163 44.7 0.184* 45.7 0.487** 68.1 Dendritic melanocytes 0.033 10.6 0.095 12.8 0.522** 59.6 melanophages 0.388** 10.6 0.230* 18.1 0.171 13.8 Cell irregularity 0.286** 24.5 0.195* 26.6 0.332** 50.0 Cell distribution 0.098 25.5 0.008 12.8 0.402** 12.8 Dots 0.231** 6.4 0.012 5.3 0.084 23.4 Roundish nests 0.026 8.5 0.102 11.7 0.296** 42.5 Structureless area 0.010 5.2 -0.042 51.1 0.365** 68.1 vessels 0.631** 32.9 0.748** 30.9 0.738** 34.0 Hyperkeratotic round concentric structures 0.159 3.2 0.216* 3.2 0.061 2.1 Network with edged papillae 0.191* 34.0 0.187* 47.9 0.340** 45.7 Network without edged papillae 0.025 13.8 0.170* 21.3 0.183* 50.0 *P=0.05. **P<0.001. Research Letter | Dermatol Pract Concept. 2024;14(4):e2024261 3 Figure 1. Optical super-high magnification pictures showing: A) vessels, B) cell irregularity, C) network with edged papillae (arrows). Appendix A-Members of Italian Optical Super-High Magnification Dermoscopy Group: Stefania Guida (School of Medicine, Vita-Salute San Raffaele University, Milan, Italy and Dermatology Clinic, IRCCS San Raffaele Scientific In- stitute, Milan, Italy), Silvana Ciardo (Dermatology Unit, Surgical, Medical and Dental Department of Morphologi- cal Sciences Related to Transplant, Oncology and Regener- ative Medicine, University of Modena and Reggio Emilia, Modena, Italy), Shaniko Kaleci (Dermatology Unit, Surgical, Medical and Dental Department of Morphological Sciences Related to Transplant, Oncology and Regenerative Med- icine, University of Modena and Reggio Emilia, Modena, Italy), Renato Rossi (Department of Dermatology, Skin Cen- ter Senigallia, Ancona, Italy), Giulia Radi (Azienda Sanitaria Territoriale Pesaro-Urbino, Pesaro, Italy), Elisa Molinelli (Dermatological Clinic Department of Clinical and Molec- ular Sciences, Polytechnic University of the Marche Region, Ancona, Italy), Carmen Cantisani (Dermatology Clinic, Department of Clinical Internal, Anesthesiological and Car- diovascular Sciences, Sapienza University of Rome, Rome, Italy), Camilla Chello (IDI-IRCCS, Dermatological Research Hospital, Rome, Italy), Marco Spadafora (Azienda Unità Sanitaria Locale-IRCCS di Reggio Emilia, Skin Cancer Cen- ter, Reggio Emilia, Italy), Sabrina Longhitano (Dermatology Unit, Surgical, Medical and Dental Department of Morpho- logical Sciences Related to Transplant, Oncology and Regen- erative Medicine, University of Modena and Reggio Emilia, Modena, Italy), Claudio Conforti (IDI-IRCCS, Dermato- logical Research Hospital, Rome, Italy), Oriana Simonetti (Dermatological Clinic Department of Clinical and Molec- ular Sciences, Polytechnic University of the Marche Region, Ancona, Italy), Franco Rongioletti (School of Medicine, Vita-Salute San Raffaele University, Milan, Italy and Der- matology Clinic, IRCCS San Raffaele Scientific Institute, Milan, Italy), Francesca Farnetani (Dermatology Clinic, University of Modena and Reggio Emilia, Modena, Italy), Caterina Longo (Dermatology Unit, Surgical, Medical and Dental Department of Morphological Sciences Related to Transplant, Oncology and Regenerative Medicine, Uni- versity of Modena and Reggio Emilia, Modena, Italy and Azienda Unità Sanitaria Locale-IRCCS di Reggio Emilia, Skin Cancer Center, Reggio Emilia, Italy), Pietro Rubegni (Dermatology Section, Department of Medical, Surgical, and Neurological Sciences, Santa Maria Alle Scotte Hospital, Siena, Italy), Anna Maria Offidani (Dermatological Clinic Department of Clinical and Molecular Sciences, Polytechnic University of the Marche Region, Ancona, Italy), Giovanni Pellacani (Dermatology Clinic, Department of Clinical In- ternal, Anesthesiological and Cardiovascular Sciences, Sapienza University of Rome, Rome, Italy), Elisa Cinotti (Dermatology Section, Department of Medical, Surgical, and Neurological Sciences, Santa Maria Alle Scotte Hospital, Siena, Italy). 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