[Secondary longitudinal melanonychia secondary to onychophagia].

BACKGROUND: Melanonychia of the toenails sometimes results from repeated trauma. This etiology is rarely put forward in lesions affecting the fingernails. CASE REPORT: A 44-year-old woman developed melanonychia affecting 9 fingernails. Genetic predisposition and drug, hormonal or infectious causes were ruled out and we postulated that the lesions were induced by nail biting. DISCUSSION: Nail biting is known to lead to several types of lesions, including melanonychia. The lesions may sometimes disappear several months after stopping this habit.