Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2024;14(1):e2024007 1 Line-Field Confocal Optical Coherence Tomography of a Suspected Case of Galli-Galli Disease Vincenzo Maione1, Francesco Tonon1, Simone Soglia1, Anna Venturuzzo1, Marina Venturini1,2, Piergiacomo Calzavara-Pinton1,2 1 Dermatology Department, University of Brescia, ASST Spedali Civili di Brescia, Brescia, Italy 2 Faculty of Medicine and Surgery, University of Brescia, Brescia, Italy Key words: Galli-Galli, LC-OCT, reflectance confocal microscopy, non-invasive tools. Citation: Maione V, Tonon F, Soglia S, Venturuzzo A, Venturini M, Calzavara-Pinton P. Line-Field Confocal Optical Coherence Tomography of a Suspected Case of Galli-Galli Disease. Dermatol Pract Concept. 2024;14(1):e2024007. DOI: https://doi.org/10.5826/ dpc.1401a7 Accepted: May 14, 2023; Published: January 2024 Copyright: ©2024 Maione 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. Francesco Tonon, Dermatology Department, University of Brescia, ASST Spedali Civili di Brescia, P. Le Spedali Civili 1 , 25123, Brescia, Italy. Phone: +390303995302 Email: f.tonon@unibs.it Introduction Galli-Galli disease (GGD) is a rare genodermatosis. Histology shows acantholysis at suprabasal level, hyperkeratosis and a downward finger-like proliferation of the rete ridges into the papillary dermis [1,2]. When histology is only partially conclusive and/or the patient refuses invasive investigations, non-invasive imaging techniques could assist the diagnosis. Coelho de Sousa et al made the first reflectance confocal mi- croscopy (RCM) evaluation of GGD [3]. Line-field confocal optical coherence tomography (LC-OCT) offers additional features compared to RCM, such as a superior penetration in depth (up to 500 μm), a dermoscopic view of the analyzed tissue, and the possibility to obtain vertical histology-like sections and 3D reconstructions of the examined tissue. To date, there are no LC-OCT descriptions of GGD. Case Presentation A 64-year-old woman presented to our clinic showing asymp- tomatic brown papules and lentigo-like macules on the trunk and extremities (Figure 1). Dermoscopy of a papule showed a central yellowish/brownish area with polygonal shape sur- rounded by a whitish halo overlying a pinkish homogeneous structureless area with harpin and linear vessels (Figure 1). These findings were similar to the acantholytic Darier and Grover diseases[4]. Lentigo-like macules showed a pseu- doreticular pattern similar to adenoid seborrheic keratosis. Histological sections from a skin biopsy exhibited hyperker- atosis, dyskeratosis and suprabasal acantholysis (Figure 1). Since the patient refused to undergo a second biopsy, we used non-invasive techniques for further investigations. We examined several papular and pigmented lesions with 2 Research Letter | Dermatol Pract Concept. 2024;14(1):e2024007 RCM (Vivascope 3000®, Caliber Imaging and Diagnos- tics): our findings were in accordance with the description of Coelho de Sousa et al (Figure 2) [3]. At LC-OCT evalua- tion (DeepLive®, DAMAE Medical) several lesions showed intraepidermal dark areas with hyper refractile roundish elements within correlating respectively to acantholysis and dyskeratotic cells, a downward finger-like proliferation of the rete ridges into the papillary dermis and basal hyper- pigmentation (Figure 2). These images were reviewed by an interdisciplinary group composed of dermatologists and pa- thologists; combining these findings with the clinical aspects, GGD was deemed to be the most likely diagnosis. Darier disease has earlier onset, seborrheic distribution of crusted yellow-brown papules rather than lentigo-like macules, nail changes and mucous membrane involvement. Grover’s dis- ease usually presents with pruritic keratotic papules on the trunk, acantholysis and dyskeratosis without elongation of the rete ridges on histology. Dowling-Degos disease was excluded because of the presence of acantholysis and the absence of comedo-like lesions and pitted perioral acnei- form scars. Conclusions An advantage of LC-OCT in diagnosing GGD is that several lesions can be studied in a relatively short time without caus- ing discomfort to patients; this could be particularly useful given that identifying features such as acantholysis on histol- ogy can be difficult and often several histological sections are needed to appreciate them [5]. Indeed, examining different cutaneous lesions can identify the most suitable sites for bi- opsy thus avoiding the need for multiple biopsies. Figure 1. (A) Clinical image of our patient showing brown macules and papules distributed on the trunk and upper extremities. (B) Dermoscopy image of a papule of the upper trunk showing a central yellow area surrounded by white halo and harpin and linear vessels. (C)  Dermoscopy image of a lentigo-like macule showing a pseudoreticular pattern. (D) Histological sections from a skin biopsy showing areas of hyperkeratosis and suprabasal acantholysis. Research Letter | Dermatol Pract Concept. 2024;14(1):e2024007 3 Non-invasive techniques represent a diagnostic tool, yet to be fully discovered, that could allow in a more conserva- tive approach to selected cases. References 1. Yang A, Cheung K, Kossard S, Murrell DF. Atypical Dissemi- nated Variant of Galli-Galli Disease: A Review of the Litera- ture. Am J Dermatopathol. 2020;42(7):484-490. DOI: 10.1097 /DAD.0000000000001467. PMID: 31449063. 2. Müller CSL, Pföhler C, Tilgen W. Changing a concept – controversy on the confusing spectrum of the reticulate pigmented disorders of the skin. J Cutan Pathol. 2009;36(1):44-48. DOI: 10.1111/j.1600-0560.2008.00995.x. PMID: 18564280. 3. Coelho de Sousa V, El-Shabrawi-Caelen L, Mendes-Bastos P, Oliveira A. Reflectance confocal microscopy for the diagnosis of Galli-Galli disease. Int J Dermatol. 2017;56(12):1501-1504. DOI: 10.1111/ijd.13677. PMID: 28703363. 4. Errichetti E, Maione V, Pegolo E, Stinco G. Dermoscopy: a useful auxiliary tool in the diagnosis of type 1 segmental Darier’s dis- ease. Dermatol Pract Concept. 2016;6(2):53-55. DOI: 10.5826 /dpc.0602a10. PMID: 27222773. PMCID: PMC4866628. 5. El Shabrawi-Caelen L, Rütten A, Kerl H. The expanding spectrum of Galli-Galli disease. J Am Acad Dermatol. 2007;56(5 Suppl):S86-S91. DOI: 10.1016/j.jaad.2006.10.987. PMID: 17434047. Figure 2. (A,B) Reflectance confocal microscopy RCM images of a hyperkeratotic papule of the trunk showing dark clefts in the epidermis with bright roundish cells within (yellow circle) (A) and branched deer antler-like refractile structure at junctional level (red arrows) (B). (C) Line-field confocal optical coherence tomography (LC-OCT) horizontal section showing an hypo-refractile area of suprabasal acanthol- ysis with dyskeratotic cells within (blue star). (D) LC-OCT 3D reconstruction of the analyzed tissue section showing downward bud-like proliferation of rete ridges into the papillary dermis (yellow line). (E) Dermoscopic view of the pigmented macule analyzed with LC-OCT.