I noticed a light black-brown vertical line on my left thumb today. I don't recall injuring it, but I'm pretty certain it wasn't there before. There's no pain or anything. Could this be something serious?
Likely to be a benign condition known as a splinter hemorrhage. It is usually harmless but can sometimes indicate an underlying medical condition. I recommend monitoring it for any changes in size or color. If you notice any changes or if it persists, you may consider consulting a dermatologist. There is no specific medication for this condition."