Subungual exostosis (bone spur under the toenail)

This condition is an outgrowth of bone below the nail of the toe (usually the Big Toe) or finger.  It can occur at any age, but 50% of reported cases are in people under 20 years of age, and the majority of patients are female.


The cause of subungual exostosis is not fully understood, although constant irritation to the bone is thought to be a factor, and previous trauma (injury) and/or longstanding infection may contribute to the development of the condition.


A firm nodule develops below the nail bed and, as it grows upwards, the nail plate separates from the bed, often causing pain. The lesion usually grows slowly over weeks to months.


The most common treatment is surgical removal. This is usually done under local anaesthetic. The tumour is then completely removed and the underlying bone is curetted (scraped clean) to prevent future recurrence.