Dermatology: Practical and Conceptual Image Letter | Dermatol Pract Concept. 2024;14(3):e2024207 1 Seven-Year Follow-Up of a Congenital Nail Matrix Nevus Cristina Guerriero1,2, Simone Cappilli1,2, Francesco Tassone1,2, Gerardo Palmisano1,2, Alessandro Di Stefani1,2, Ketty Peris1,2 1 Dermatologia, Dipartimento di Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, Rome, Italy 2 UOC di Dermatologia, Dipartimento di Scienze Mediche e Chirurgiche, Fondazione Policlinico Universitario A. Gemelli - IRCCS, Rome, Italy Citation: Guerriero C, Cappilli S, Tassone F, Palmisano G, Di Stefani A, Peris K. Seven-Year Follow-Up of a Congenital Nail Matrix Nevus. Dermatol Pract Concept. 2024;14(3):e2024207. DOI: https://doi.org/10.5826/dpc.1403a207 Accepted: March 24, 2024; Published: July 2024 Copyright: © Guerriero 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: Simone Cappilli, MD, PhD candidate, UOC di Dermatologia, Dipartimento di Scienze Mediche e Chirurgiche, Fondazione Policlinico Universitario A. Gemelli - IRCCS, Rome, Largo A. Gemelli 8, 00168 Rome, Italy. Tel: +39 06-30154227 - Fax: +39 06-30154919. Email: simo.cappilli@gmail.com Case Presentation An otherwise healthy 4-year-old boy presented with a nail pig- mentation of the second right toe that the parents reported he had had since birth. Clinically, we observed a melanonychia striata longitudinalis involving ⅓ to ⅔ of the nail, and on der- moscopy, homogeneous light-to-dark brown nail bands and fibrillar pattern on the proximal nailfold (micro-Hutchinson sign) (Figure 1). A diagnosis of congenital nail matrix nevus was thus established, and clinical monitoring over time was scheduled. At follow-up visits over the following seven years, we noticed significant changes in nail pigmentation. He had developed two dark broad bands involving at least the entire nail plate. Dermoscopic changes were related to longitudi- nal bands acquiring an irregular pattern with heterogeneous thickness, spacing, and color (Figure 1). Teaching Point Subungual melanocytic lesions in children are mainly due to congenital and congenital-type nail matrix nevi [1]. These benign entities may show an atypical clinical presentation, with a broad pigmentation involving up to the entire nail plate, associated with micro-Hutchinson sign and irregular dermoscopic criteria [2]. Considering the rarity of subun- gual melanoma in children, with just 21 cases described to date, and the higher frequency of benign longitudinal mela- nonychia, melanocytic lesions of the nail should be man- aged differently in this setting than in adults [1,2]. In most cases, a watch-and-wait monitoring strategy is the most appropriate approach, avoiding a biopsy of the nail ma- trix, often complicated by nail dystrophy and permanent scarring. 2 Image Letter | Dermatol Pract Concept. 2024;14(3):e2024207 References 1. Pham F, Boespflug A, Duru G, et al. Dermatoscopic and clini- cal features of congenital or congenital-type nail matrix nevi: A multicenter prospective cohort study by the International Der- moscopy Society. J Am Acad Dermatol. 2022; 87(3): 551-558. DOI:10.1016/j.jaad.2022.01.028. 2. Lallas A, Korecka K,Apalla Z, et al. Seven Plus One Steps To Assess Pigmented Nail Bands (Melanonychia Striata Longitu- dinalis). Dermatol Pract Concept. 2023;13(4):e2023204. DOI: https://doi.org/10.5826/dpc.1304a204 Figure 1. Clinical and dermoscopic evolution of melanonychia striata longitudinalis. (A-D) Dark brown pigmentation with a gradual vari- ation of the width after 2, 4, and 7 years. (E-H) Dermoscopy shows regular nail bands turning heterogeneous in number and size over time.