Subungual Exostosis

What is a subungual exostosis?

A subungual exostosis is a small bony outgrowth that develops underneath or beside a toenail — most commonly the big toe. It's a benign bone-and-cartilage growth, but its location means it often causes problems with the nail and surrounding skin.

The cause isn't always clear. Sometimes there's a history of injury to the toe; in other cases it appears without obvious provocation. It's most often seen in older children and adolescents.

It can be confused with other conditions — warts, infections or other lesions of the nail bed — so getting the diagnosis right matters.

What does it feel like?

Common features include:

• Pain or pressure under or beside the toenail

• A visible firm lump under or alongside the nail

• Nail deformity — lifting, splitting or unusual growth

• Discomfort when wearing shoes

• Sometimes a wound or persistent skin issue over the area

Symptoms can be persistent and slowly progressive. They often don't respond well to treatments aimed at presumed warts or fungal nail problems, which is one reason the correct diagnosis matters.

How is it diagnosed?

Examination of the nail and the surrounding tissue raises the suspicion. X-rays of the toe usually confirm the diagnosis by showing the bony outgrowth — they're the most useful single investigation.

Sometimes additional imaging or a small biopsy is arranged when the diagnosis isn't clear or to exclude other lesions.

The assessment also considers any contributing factors and the impact on the child's daily activities.

What are the treatment options?

Symptomatic subungual exostoses are usually treated with surgical removal of the bony outgrowth, often as a small day-case procedure. Recovery is typically quick.

Asymptomatic outgrowths sometimes don't need any specific treatment beyond observation. The decision and timing are individual — Nev will work through what's right for your child at your consultation.

When should you get it checked?

Seek a specialist assessment if:

• There's persistent pain under or beside a toenail

• The nail is deformed or growing abnormally

• There's a visible lump in the nail area

• Treatments for presumed warts or infections haven't worked

• You want a clear diagnosis and treatment plan

Subungual exostosis is a recognisable but sometimes underdiagnosed condition. A clear diagnosis opens up the right treatment quickly and avoids prolonged, ineffective alternatives.