Like other exostosis this is a enlarged portion of bone. Subungual refers to the bone being underneath the toenail.

Symptoms of a subungual exostosis may be severe pain to the nail. The toenail may also become peaked as there is pressure place on the middle of the nail from this bone structure. It may cause onychocryptosis, or ingrown toenails.

Causes of a subungual exostosis may be unknown. The bone may be formed because of your foot structure you were born with, or deformity in the bone maybe caused by some trauma.

Diagnosis of a subungual exostosis is sometimes difficult. An x-ray is usually taken to see if a spur on the bone is seen.

Podiatric Care of a subungual exostosis is usually by relieving the pressure of the spur on the nail or other external pressures. Wearing a shoe with a larger toe box can take pressure off of the big toe. The nail may be trimmed or thinned using a small burr. Padding techniques such as tube foam to relieve pressure may work to relieve pressure. Failure of these techniques may require a small surgical procedure to entirely remove the nail permanently as is done for an ingrown nail. If the toenail is not permanently removed there is a good chance for reoccurrence. An additional procedure may be done to remove this extra formation of bone on the top of the toe.