Treatment of Benign Melanocytic Hyperplasia of Nail apparatus with Dr. HoonHur's Golden Parameter Therapy This dark line or discoloration on the nail can be a common condition called melanonychia, basically, extra pigment in the nail plate. In many people, especially those with more melanin in their Pigmented Nail Lesions: When to Observe, When to Biopsy, When to Widely Excise, and When to Amputate? Journal of Hand Surgery Differential diagnosis of pigmented nail lesions Anais Brasileiros de Dermatologia