Pigmented Nail Lesions: When to Observe, When to Biopsy, When to Widely Excise, and When to Amputate? Journal of Hand Surgery 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 LaugierHunziker syndrome: a report of three cases and literature review International Journal of Oral Science Pigmented Nail Disorders Basicmedical Key Longitudinal melanonychia and skin hyperpigmentation associated with hydroxychloroquine therapy JAAD Case Reports An Evidence Based Approach to Pediatric Melanonychia Dermatologic Clinics