Metastatic olfactory neuroblastoma with unusual solitary metastasis to femur: a case report and literature review.

Background: Olfactory neuroblastoma (ONB) is a rare malignancy that develops in the nasal cavity, with appendicular skeletal metastases being exceptionally uncommon. We report the case of a middle-aged male with ONB, presenting with an unusual biopsy-confirmed solitary metastasis to the left proximal femur.

Case presentation: A 33-year-old male was previously diagnosed with olfactory neuroblastoma in the skull base after initial clinical presentation with progressive left-sided nasal obstruction for six months. He was treated with neoadjuvant chemotherapy, followed by local control via trans-sphenoidal resection in addition to postoperative radiotherapy and adjuvant chemotherapy. Two years later, the patient began experiencing left thigh pain. Radiographic imaging of the left femur revealed an ill-defined lesion in the midshaft with periosteal thickening, suggesting metastatic disease. The lesion caused significant bone destruction, ending up with a non-traumatic pathological fracture. A wide surgical resection of the proximal two-thirds of the femur was performed, followed by endoprosthetic reconstruction to restore structural integrity, joint function, and limb biomechanics. Postoperative management included physical rehabilitation to optimize functional recovery and maintain weight-bearing capacity.

Conclusion: This case underscores the importance of early identification of skeletal involvement in ONB, as prompt orthopedic intervention can prevent complications, improve mobility, and contribute to better oncological and functional outcomes. Advanced reconstructive techniques play a pivotal role in achieving durable results in cases involving skeletal metastasis of rare tumors like ONB.