[Striped nail pigmentation with Hutchinson signs in a boxer]

We present a 68-year-old male patient, who had had longitudinal melanonychia with Hutchinson sign for 4 years. Melanocytic proliferation was ruled out by biopsy. Friction and pressure had been acting on this patient's nails during boxing for the past 40 years. These mechanical factors are discussed under the entity of "frictional longitudinal melanonychia". In addition, cellular and non-cellular mechanisms for longitudinal melanonychia are reviewed.