A 8-year-old boy presented with a 4-month history of a 1-cm erythematous, friable nodule on the distal phalanx of the left second finger. There was no history of trauma. Based on the clinical characteristics of the lesion, the diagnosis of pyogenic granuloma was assumed, and curettage of the lesion was performed. The histopathological examination was nonspecific. Two weeks later, a 1-cm flesh-colored nodule with nail elevation and onycholysis appeared in that location (Fig. 1a). The diagnosis of subungual exostosis was confirmed by radiography, revealing a calcifying projection on the dorsal part of the distal phalanx (Fig. 1b). Surgical resection of the lesion was performed.
Subungual exostosis is an uncommon benign bone tumor. Most lesions occur during the second or third decades of life. Although it can manifest itself in any finger, 70–80% of cases appear on the distal phalanx of the hallux. Its similarities with other dermatologic disorders involving the nail bed, such as warts, granulomas pyogenic, fibrokeratomas, and periungual fibromas, can lead to misdiagnosis, which may result in inadequate treatments.
With this case, we intend to put forward the idea that, although rare, subungual exostosis can occur in the hands of children and, therefore, must be considered.
