Skip Lesion in Distal Femur with Recurrent Giant Cell Tumor of the Proximal Femur: A Very Rare Case Managed with Excision, Megaprosthesis Reconstruction, and Bone Cement Curettage.

Introduction: Giant cell tumor (GCT) of bone is a benign but locally aggressive tumor, commonly affecting the epiphysis of long bones in young adults. Skip lesions in GCT - defined as discontinuous tumor foci within the same bone - are exceedingly rare, particularly in the appendicular skeleton. Simultaneous recurrence and skip lesions in the same bone have been rarely documented. Case Report: We report a rare case of a 21-year-old female with a recurrent GCT of the proximal femur, previously treated with curettage, bone cementing, and fixation. Two years post-recurrence, she developed a skip lesion in the distal femur along with pulmonary metastases. Management included neoadjuvant denosumab, excision of the proximal lesion with megaprosthesis reconstruction, and curettage and cementation of the distal lesion with plate fixation. Post-operative follow-up showed significant clinical improvement and no recurrence or metastasis progression. Conclusion: This case highlights an exceptionally rare presentation of recurrent GCT with a skip lesion in the same bone and asymptomatic pulmonary metastases. Early recognition, appropriate imaging, and a multidisciplinary approach - including denosumab therapy and surgical reconstruction - are essential for favorable outcomes in such aggressive and atypical cases.