Osteochondromas are benign bone tumors under the toenail. They form in the bone beneath the toenail. An osteochrondroma accounts for about half of all benign bone tumors, occurring mostly in children and young adults. Unless they cause irritation to the surrounding tissue, they are generally not very painful.
Sometimes, they can deform the toenail and cause an ingrown toenail. In some cases, they are removed surgically, but can recur even after the procedure.