(P 509) GIANT CELL TUMOR OF BONE IN THE PEDIATRIC POPULATION: A RETROSPECTIVE STUDY HIGHLIGHTING CASES OF METAPHYSEAL ONLY LOCATION AND INCREASED LOCAL RECURRENCE RATES IN SKELETALLY IMMATURE PATIENTS

Objective: To describe the presentation of giant cell tumors of bone (GCT) in the pediatric population to 1) improve the differential diagnosis of pediatric bone tumors and 2) identify the origin of GCT. Understanding the origin of bone tumors assists in establishing appropriate diagnoses and recommending treatment options. This is particularly important in children, where evaluating the need for invasive procedures is balanced with the desire to avoid overtreatment. GCT have historically been considered epiphyseal lesions with potential metaphyseal extension. Therefore, GCT may be inappropriately excluded from the differential diagnosis of metaphyseal lesions in the skeletally immature.

Methods: We identified 14 patients from 1981- 2021 at a single institution who had histologic confirmation of GCT and were less than 18 years old at diagnosis. Patient characteristics, tumor location, surgical treatment, and local recurrence rates were collected.

Results: Ten (71%) patients were female. Eleven (78.6%) were epiphysiometaphyseal (1 epiphyseal, 4 metaphyseal, 6 epiphysiometaphyseal). Five patients had an open adjacent physis, of which three (60%) had tumors confined solely to the metaphysis. Of the five patients with open physis, four (80%) developed local recurrence while only one patient (11%) with a closed physis had local recurrence (p value = 0.0023).

Conclusion: Our results illustrate that for the skeletally immature, GCT can (and in our results more commonly did) occur in the metaphyseal location. These findings suggest that GCT should be included in the differential diagnosis of primary metaphyseal only lesions in the skeletally immature.