A darkened nail on the big toe requires careful observation of the nail’s appearance. If the blackened nail is mainly dotted and gradually spreads outward as the nail grows, consider that the bruising under the nail has been caused by external stimulation and extrusion. It is recommended to reduce external stimulation of the thumb nail, and over time, the underfoot bruising will gradually grow outward until it is completely removed and can recover on its own. If the bunion is black and the color is not particularly noticeable, consider that it has been exposed to certain dyes and can be cleaned with alkaline cleaning products. If the blackened area is streaked and dark, it is considered to be a nail nevus. It is recommended to go to the local hospital for dermoscopic examination and, if necessary, nail extraction to remove the nail nevus completely under the skin for pathological examination.