Subungual Exostosis

A subungual exostosis is typically the result of an injury to the toe - this might be stubbing your toe, dropping something on it or someone demonstrating a lack of love for you with their heel.

As the nail grows forward over the bone in your toe, the nail has to either grow straight into the skin or up and over. This can cause the nail to either grow in a very rounded shape - turning it into a pincer nail, or can cause it to have a large growth coming out from under the nail.