A remarkable and aggressive aneurysmal bone cyst ravaging the femoral shaft, advancing to lung metastases: An extremely rare case

INTRODUCTION AND IMPORTANCE: Aneurysmal bone cysts (ABCs) are relatively uncommon tumor-like lesions that require careful management. Reporting such cases is crucial to highlight the importance of understanding the physiopathology and treatment options associated with ABCs. Literature-based writing emphasizes the significance of reporting cases like the one presented here. The aneurysmal bone cyst, classified as a Tumor Rich in Giant Cells according to the latest World Health Organization (WHO) classification of soft tissue and bone tumors, has posed several hypotheses and challenge. This aggressive form and rare localization of this lesion necessitates thorough discussions regarding its management. CASE PRESENTATION: We present a compelling case of a 37-year-old patient, without any specific pathological history, with a giant diaphyseal aneurysmal bone cyst located in the right femur. Remarkably, the lesion had been progressing for a decade, leading to extensive destruction of the entire femoral diaphysis despite undergoing previous surgical interventions. The patient's unique circumstances highlight the unpredictable behavior and destructive potential of aneurysmal bone cysts in rare anatomical locations. DISCUSSION AND CONCLUSION: This case underscores the need for a comprehensive understanding of aneurysmal bone cysts and their management. The utilization of denosumab, an inhibitor of the RANK/RANKL system, as a medical treatment in conjunction with surgery resulted in a favorable therapeutic response, including a reduction in tumor mass. The current WHO classification, recognizing ABCs as Tumors Rich in Giant Cells, consolidates previous hypotheses and enables the development of new therapeutic protocols. The integration of surgery and medical treatment holds promise for improving outcomes in patients with aneurysmal bone cysts. In conclusion, advancements in understanding the physiopathology and treatment options are crucial for developing effective therapeutic protocols to these aggressive forms of ABCs.