Melanonychia

What it means

Dark discoloration of a fingernail or toenail (brown, black, bluish and reddish).

The most serious disease of the nail unit, melanoma, primarily presents with melanonychia. However, melanonychia most often occurs as a result of benign etiologies such as nail matrix melanocytic activation, nail matrix melanocytic hyperplasia, subungual hematoma, glomus tumor, and nail invasion by melanin-producing pathogens.

Rare diseases that can present with this2

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Dark discoloration of nail