I just noticed a light black/brown vertical line on my left thumb today. I dont remember injuring it or anything, and Im sure it wasnt there before. Theres no pain, but Im worried if this could be something serious. Should I be concerned?

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."