A Case of Subungual Exostosis With Early Postoperative Recurrence and Rapid Growth.

Subungual exostosis is a relatively rare benign bone tumor that occurs near the distal phalanges of the fingers and toes. Though it is similar to osteochondroma, it can be distinguished by its specific location and lack of communication with the medullary cavity. Although recurrence after surgical excision has been reported, no studies have examined the timing or progression of recurrence, nor have there been reports detailing the chronological imaging findings of recurrent cases. A case of subungual exostosis that recurred rapidly with significant growth shortly after surgical excision is reported. The patient was a 13-year-old boy with subungual exostosis of the fourth toe. Tumor recurrence was observed four weeks after the initial excision, and it gradually enlarged, growing to several times the size of the original tumor three months after surgery. A second procedure was performed approximately four months after the initial procedure, and no recurrence has been observed since. This case represents the first report of the chronological radiographic progression of recurrent subungual exostosis, highlighting the importance of careful follow-up and consideration of early recurrence after excision.