PMC9902096_01
Preoperative clinical photograph of the 10-year-old female patient. A nail deformity was noted on the left third toe.
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After 7 months, her nail deformity became worse with severe pain and a protruding mass was noted under the edge of toenail ( Fig. 1 ).
Preoperative anteroposterior view X-ray image. An exophytic lesion was noted on the left third toe.
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An anteroposterior X-ray of the toe revealed an exostotic mass of the distal phalanx suspicious for a primary bone tumor ( Fig. 2 ).
Intraoperative clinical photograph including the surgical specimen.
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In the operative field, we could observe a 0.5-cm well-demarcated granulating round mass after extracting the deformed toenail ( Fig. 3 ).
Histopathological findings of subungual osteochondroma. The lesion showed a cartilaginous cap composed of mature hyaline cartilage and fragments of bone trabeculae with endochondral ossification. The chondrocytes were observed within mature hyaline cartilage (hematoxylin-eosin stain, original magnification x200).
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 The final pathology report after surgery confirmed subungual osteochondroma that showed a cartilaginous cap composed of mature hyaline cartilage and fragments of bone trabeculae with endochondral ossification ( Fig. 4 ).
Postoperative clinical photograph at the 3-month follow-up visit.
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The patient returned for a regular follow-up visit 4 months after surgery without tumor recurrence, showing an intact toenail ( Fig. 5 ).
PMC9902096_02
Preoperative clinical photograph of the 15-year-old male patient. A nail deformity was noted on the great toe of the right foot.
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About 6 months later, his nail deformity progressed, showing mass formation under the toenail ( Fig. 6 ). 
Histologic findings showed an osteochondroma. The pathologic lesion is composed of a cartilage cap and mature bony trabeculae (hematoxylin-eosin stain, original magnification x100).
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The specimen had mature bone trabeculae with a focal cartilaginous cap and fibrous tissue, consistent with subungual osteochondroma ( Fig. 7 ).
Postoperative clinical photograph at the 6-month follow-up visit.
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The healing process assisted adequate nail growth, and intact perionychium was observed at the 6-month postoperative follow-up ( Fig. 8 ).