Abstract
INTRODUCTION AND IMPORTANCE: Adamantinomas are rare, low-grade, malignant skeletal tumors accounting for only 0.33-0.48 % of primary malignant bone tumors. CASE PRESENTATION: An 11-year-old boy with adamantinoma of the ulna was treated with en bloc resection, kryptonite bone cement, and plate fixation. The surgery resulted in marked pain relief and good functional recovery. No evidence of recurrence was observed for 5 years postoperatively, and the Musculoskeletal Tumor Society score was 93. CLINICAL DISCUSSION: This case of an 11-year-old previously treated for an aneurysmal bone cyst (ABC) illustrates the complexity of diagnosing adamantinoma, especially in atypical locations like the ulna. The successful use of en bloc resection and synthetic bone graft highlights the importance of accurate diagnosis and advanced surgical methods in achieving favorable outcomes in pediatric orthopedic oncology. CONCLUSION: Ulnar adamantinomas are rare and can be difficult to diagnose. The successful treatment of this tumor, as described in this case report, can help guide the management of similar cases in the future.