A painful lump lifting the nail

A subungual exostosis is a small, benign bony growth that arises from the tip of a toe bone (the distal phalanx) and pushes up underneath or just beyond the nail. It most often affects the big toe in adolescents and young adults. Patients typically notice a firm bump that lifts or deforms the nail, pain with pressure from shoes, and sometimes a reddish, thickened area of skin over it that can catch, bleed, or become infected.

Despite the name, it is not a true tumor of concern. It is made of normal bone capped by fibrocartilage, and it is thought to be provoked by trauma or chronic irritation — repetitive stubbing, tight shoes, or minor injury to the toe tip.

How it’s diagnosed

The diagnosis is usually straightforward. A simple X-ray shows the bony outgrowth projecting from the top of the distal phalanx and confirms it at once. This is important because a subungual exostosis can be mistaken for an ingrown toenail, a wart, or chronic granulation tissue — so a firm bump under the nail that doesn’t settle deserves an X-ray rather than repeated nail treatments. A related lesion, subungual osteochondroma, looks similar and is managed the same way.

Treatment

There is no medication or cream that removes the bony growth; if it is painful, deforming the nail, or repeatedly getting irritated, the definitive treatment is surgical excision. Through a small incision at the tip of the toe — sometimes after lifting or partially removing the nail to reach it — the surgeon removes the exostosis flush with the underlying bone, taking care to excise the fibrocartilage cap completely. The nail bed is then repaired so the nail can regrow normally.

The operation is typically done as a day procedure under local anesthesia. Removing the lesion cleanly at its base is what matters most, because an incompletely excised growth is the main reason a small number recur.

Recovery and outlook

Recovery is generally quick. The toe is dressed and protected, patients usually walk in a stiff-soled or open postoperative shoe, and the wound heals over a couple of weeks. If the nail was lifted or partially removed, it grows back gradually over several months. The outlook is excellent — the lesion is benign, pain is reliably relieved once it is removed, and recurrence is uncommon when the excision is complete. Recovery timelines vary from person to person, and your progress will be reviewed at each visit.

This article is for general education and is not a substitute for individual medical advice.