Soccer player with painful toe

Diagnosis: Subungual exostosis

A plain radiograph of the patient’s foot showed continuity with the bony cortex and medullary space, confirming the diagnosis of subungual exostosis (FIGURE 2).¹ An exostosis, or osteochondroma, is a form of benign bone tumor in which trabecular bone overgrows its normal border in a nodular pattern. When this occurs under the nail bed, it is called subungual exostosis.² Exostosis represents 10% to 15% of all benign bone tumors, making it the most common benign bone tumor.³ Generally, the age of occurrence is 10 to 15 years.³

Repetitive trauma can be a culprit. Up to 8% of exostoses occur in the foot, with the most commonly affected area being the distal medial portion of the big toe.^3,4 Repetitive trauma and infection are potential risk factors.^3,4 The affected toe may be painful, but that is not always the case.⁴ Typically, lesions are solitary; however, multiple lesions can occur.⁴

Most pediatric foot lesions are benign and involve soft tissue

Benign soft-tissue masses make up the overwhelming majority of pediatric foot lesions, accounting for 61% to 87% of all foot lesions.³ Malignancies such as chondrosarcoma can occur and can be difficult to diagnose. Rapid growth, family history, size > 5 cm, heterogenous appearance on magnetic resonance imaging, and poorly defined margins are a few characteristics that should increase suspicion for possible malignancy.⁵

The definitive treatment for subungual exostosis is surgical excision, preferably once the patient has reached skeletal maturity.

The differential diagnosis for a growth on the toe similar to the one our patient had would include pyogenic granuloma, acral fibromyxoma, periungual fibroma, and verruca vulgaris.

Pyogenic granulomas are benign vascular lesions that occur in patients of all ages. They tend to be dome-shaped and flesh-toned to violaceous red, and they are usually found on the head, neck, and extremities—­especially fingers.⁶ They are associated with trauma and are classically tender with a propensity to bleed.⁶

Acral fibromyxoma is a benign, slow-growing, predominately painless, firm mass with an affinity for the great toe; the affected area includes the nail in 50% of cases.⁷ A radiograph may show bony erosion or scalloping due to mass effect; however, there will be no continuity with the bony matrix. (Such continuity would suggest exostosis.)

Periungual fibromas are benign soft-tissue masses, which are pink to red and firm, and emerge from underneath the nails, potentially resulting in dystrophy.⁸ They can bleed and cause pain, and are strongly associated with tuberous sclerosis.⁵

Continue to: Verruca vulgaris