Dermoscopy of Onychopapilloma: A Benign Mimic of Subungual Malignancy.

Onychopapilloma is a benign tumor of the nail bed and distal matrix, commonly presenting with longitudinal erythronychia and distal subungual hyperkeratosis. A 30-year-old Asian male presented with an asymptomatic, stable discoloration of the thumbnail, with longitudinal erythronychia, distal onycholysis, and V-shaped fissuring. Dermoscopy revealed splinter hemorrhages and focal distal subungual hyperkeratosis beneath the V-shaped notch. The lesion was unchanging over several years, and the patient opted for conservative management with periodic monitoring rather than biopsy. Based on clinical and dermoscopic features, onychopapilloma can often be distinguished from malignant conditions such as amelanotic melanoma and squamous cell carcinoma. Differential diagnoses include glomus tumor, trauma, Darier disease, and lichen planus. While biopsy is not needed for stable, asymptomatic cases, it is recommended if the lesion changes or becomes symptomatic.