Paediatric Melanonychia: Diagnosis and Management

ABSTRACT Longitudinal melanonychia (LM) in children presents unique diagnostic and management challenges that cannot be adequately addressed by applying adult‐based criteria. Unlike in adults, there are no validated clinical, dermoscopic or histopathologic criteria for predicting nail unit melanoma in the paediatric population. Clinical and histopathologic features of paediatric LM frequently overlap with findings considered concerning in adults, creating significant diagnostic uncertainty. A narrative review of the literature was performed by querying PubMed using the search terms ‘paediatric melanonychia’, ‘childhood melanonychia’, ‘nail matrix naevus’, ‘subungual melanoma’ and ‘longitudinal melanonychia’ combined with ‘paediatric’ or ‘childhood’. Additional relevant articles were identified through manual review of reference lists. No date restrictions were applied, and only English‐language articles were included. This review offers a practical, evidence‐based approach to the diagnosis and management of paediatric LM. We discuss how clinical and dermoscopic features can mimic adult subungual melanoma and review the histopathologic challenges unique to this population. We also examine the natural history of paediatric LM, highlighting longitudinal data demonstrating that nail matrix nevi can progress and regress over time. Careful observation is one of the most informative diagnostic tools available. The overwhelming majority of paediatric LM cases are benign, most commonly representing nail matrix melanocytic nevi. Most experts support a conservative approach centred on longitudinal clinical monitoring with serial photography and dermoscopy, reserving surgery for cases demonstrating rapid progression or markedly atypical features. Ongoing efforts to refine risk stratification, establish age‐appropriate diagnostic criteria and generate longitudinal outcome data are essential to optimizing care while minimizing unnecessary invasive procedures in this population.