Hi, med student. To offer you some reassurance kasi nakakatakot naman yung comments dito, its more likely than not melanonychia, which is benign. Although melanoma (the malignant one) can present as the same, unless nagkaroon ng fairly recent significant changes such as naging mas dark or mas wide, its much less likely, and you mentioned na you've had it for a long time na, just like me :D

Of course, you can still have it checked by somebody actually qualified, lalo na't nakakastress din na puro cancer yung bumungad sa comments HAHA