Supplementary Material for: Dermoscopy of Subungual Exostosis: A Retrospective Study of 10 Patients

<i>Introduction:</i> Subungual exostosis (SE), the most common nail tumor of young adults, is a benign bony proliferation of the distal phalanx occurring beneath the nail. Misdiagnosis or late diagnosis frequently occurs and no dermoscopy features of this tumor were previously outlined. <i>Material and Methods:</i> To describe the dermoscopic appearance of SE, 10 patients with radiologically and histologically confirmed SE were retrospectively retrieved from our tertiary referral centers. Data regarding age, gender, time to diagnosis, clinical presentation, dermoscopic features, involved nail and history of trauma were recorded for each patient. <i>Results:</i> In our patients, clinical findings were similar to previous reports. Among the dermoscopic features, vascular ectasia was the most common finding (70%), followed by hyperkeratosis (60%), onycholysis (40%), and ulceration (30%). <i>Conclusion:</i>Dermoscopy could be a useful technique aimed at creating diagnostic suspicion of this benign nail condition, although X-ray examination and histopathology are mandatory for the diagnosis.