Case Report: Giant cell reparative granuloma of the humerus and femur-two rare cases with atypical skeletal involvement.

Introduction: Giant cell reparative granuloma (GCRG) is a rare benign lesion that typically arises in the mandible and maxilla, whereas involvement of the long bones is extremely uncommon. It is generally considered a reactive, non-neoplastic process associated with prior trauma or surgical intervention. Case report: We report two rare cases of GCRG involving the extremities: one in the proximal humerus and the other in the distal femur. Both patients had a history of prior mechanical strain or localized trauma. Imaging revealed well-defined expansile osteolytic lesions with heterogeneous internal features and contrast enhancement, initially mimicked giant cell tumor of bone. Surgical intervention was performed in both cases, and the diagnosis of GCRG was confirmed by postoperative histopathological examination. Conclusion: These cases underscore the importance of including GCRG in the differential diagnosis of osteolytic lesions at atypical skeletal sites, particularly in patients with a history of trauma. Accurate diagnosis relies on the integration of radiologic and histopathological findings to prevent misdiagnosis and guide appropriate management.