Two distinctive subungual pathologies: Subungual exostosis and subungual osteochondroma

Background: The purpose of this study was to present features that differentiate subungual exostosis from subungual osteochondroma. Methods: We treated 11 patients for subungual masses. All were confirmed by radiographic and histologic evaluations to be subungual exostosis or subungual osteochondroma. The study patients comprised eight female and three male patients with a mean age at presentation of 18.7 years (range 1.5 to 70.9). In the five patients with subungual exostosis, three (60%) had a toe lesion, and two (40%) had a finger lesion. In the six patients with subungual osteochondroma, four (67%) had a toe lesion, and two (33%) had finger lesions. We analyzed the clinical features, including trauma history, the existence of infection before surgery, tumor recurrence, and postoperative nail deformity. Results: In all patients, the lesions presented as an exophytic tumor of the nail apparatus, beneath the nail plate, which varied in size from 0.6 x 0.4 cm to 1.2 x 0.9 cm. Excision of these masses produced useful toes or fingers without pain, a tender sear, or nail deformity. Although nails were deformed preoperatively, they grew back without ridges or cracks within 3 to 5 months postoperatively. There were no recurrences based on clinical and radiographic evaluations, and both tumor types showed characteristic radiographic and histologic differences. Conclusions: Subungual exostosis and subungual osteochondroma are benign but have distinct osseous pathologies. We concluded that subungual exostosis is clinically, developmentally, radiographically, and histologically distinct from subungual osteochondroma.