Brown black pigmented nail bands (melanonychia) can be a sign of subungual melanoma. This case report describes a child with melanonychia mimicking melanoma caused by green slime. Presumably, the slime embedded in the Pigmented Lesions of the Nail Unit: Clinical and Histopathologic Features Melanonychia: What It Is, Causes, and More Noticed a dark streak on your nail? It could be melanonychia a condition where pigmentation appears in the nail plate, often as a brown or black line. While it's commonly 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