Given the knee pain, the patient in this case underwent resection of the distal femoral lesion and total knee replacement. Histopathological examination confirmed that the lesion in the medial femoral condyle was a metastasis from lung squamous cell carcinoma.

This case demonstrates an uncommon presentation of metastasis to the distal femur from primary lung carcinoma. A distal bone metastasis is more likely to be from a lung primary tumor, since a lung tumor can directly enter the pulmonary venous system, flowing through into the systemic arterial circulation.