January 01, 2013
2 min read

A 12-year-old girl with a warty lesion on her toe

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A 12-year-old female presents with a verrucous papule on the distal end of her right third toe. The lesion has been present for approximately 1 year and has been growing slowly over that time. The patient notes a history of trauma to the toe (“I stubbed it really hard a few months ago!”) prior to first noticing the papule. The papule is neither painful nor pruritic. She denies any prior treatment, and she does not have any other similar lesions. The family is convinced this is a wart and would like to know more about in-office treatment options.

Shehla Admani

Andrew C. Krakowski

On physical exam, the patient is noted to have a hard exophytic mass at the distal end of her right third toe (Top photo). The lesion is non-tender and has some overlying small visible blood vessels. Her other toes appear completely normal. She has no other verrucous papules on her body.

What is the next step in this patient’s care?

A. Punch biopsy
B. Liquid nitrogen treatment
C. X-ray of the toe
D. Home treatment with salicylic acid and duct tape
E. B and D
Hint: It’s not a wart!

Subungual exostosis (SE) is a benign bone tumor that is often misdiagnosed as a wart. The deformity was first described by Guillaume Dupuytren in 1817. It consists of an osteocartilaginous mass on the dorsal surface of the distal phalanx, most commonly seen on the great toe, but it can also be found on other digits. The exact pathogenesis is unclear; however, antecedent trauma, chronic irritation and chronic infection are thought to play a role in the development of these lesions. Differential diagnosis for SE includes subungual verruca; onychomycosis; subungual fibroma; pyogenic granuloma; keratoacanthoma; glomus tumor; myositis ossificans; and, importantly, melanoma.

A common clinical history is that of a stubborn wart that has not improved after several attempts at treatment. Although SE is a benign lesion, a misdiagnosis or delay in diagnosis can lead to severe implications. If not correctly diagnosed, the lesion can continue to grow for months and result in detachment of the overlying nail. The exposed nail bed and/or surrounding tissue can ulcerate and develop a secondary periungual infection. Patients can develop paronychia, pain and deformity of the digit.

Top photo: Right third toe with exophytic, non-tender mass. Bottom photo: X-ray of right third toe showing a subungual exostosis emanating from the distal phalanx.

The diagnosis of SE is both clinical and radiological. Radiographs will show a sessile or pedunculated expansion of bone covered in cartilage, with no evidence of cortical disruption or any abnormality of the distal phalanx. Biopsy is not recommended until the full extent of the lesion has been evaluated. Treatment with surgical excision is usually curative. A variety of surgical techniques have been described.

Some experts recommend waiting until maturation of the lesion has occurred, which allows the development of cleavage planes and ensures that total excision is possible. Others recommend entire nail removal to ensure the entire lesion has been excised. Total or partial nail bed resection may cause significant pain, nail deformity and delay in return to daily activity. Another option consists of total excision with a thin area resection of nail bed, which ensures complete tumor removal and avoids the complications associated with total nail removal.

The patient in our case had an X-ray performed of her right third toe (Right photo), which showed a subungual exostosis emanating from the distal phalanx and pointing superiorly. She is scheduled to see pediatric orthopedic for surgical excision.


De Berker DA. Br J Dermatol. 1999;140:915-918.

For more information:

Shehla Admani, MD, is a clinical research fellow in pediatric dermatology at Rady Children’s Hospital, San Diego. She can be reached at 8010 Frost St., Suite 602, San Diego, CA 92123; email: sadmani@rchsd.org.
Andrew C. Krakowski, MD, is an attending physician at Rady Children’s Hospital, San Diego.

Disclosure: Admani and Krakowski report no relevant financial disclosures.