Nail changes can reveal major systemic disease, from cirrhosis and endocarditis to melanoma., Splinter hemorrhages + fever murmur should make you think of infective endocarditis., Single 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 Dermoscopic features of nail matrix nevus (NMN) in adults and children: A comparative analysis ScienceDirect Diagnosis and Treatment of Pigmented Nail Lesions