Diving under Nail Plate

A 43-year-old Bolivian woman presented with nail dystrophy involving the right fifth toe of 4 years’ duration. It had become painful only a few weeks earlier. She was otherwise healthy and denied other significant medical history. Physical examination revealed xanthonychia, diffuse longitudinal thickening with transverse overcurvature, and mild periungual erythema. The nail plate was removed and a filamentous tumour arose from the matrix (Fig. 1). It was histologically analyzed (Fig. 2). What is your diagnosis? Received: November 2, 2016 Accepted: July 26, 2017 Published online: September 13, 2017