Proximal tibial extra-axial chordoma masquerading as renal cell carcinoma metastasis.

Chordomas are rare, locally aggressive notochordal tumors, which most frequently occur in the neuraxis. We describe the case of a 74-year-old male with a history of renal cell carcinoma, who presented with a slowly enlarging mass in his left leg. While the clinical history and imaging suggested metastatic renal cell carcinoma, immunohistochemical staining with brachyury ultimately made the diagnosis of extra-axial chordoma. At 74 years of age, our patient is the oldest ever reported with bony extra-axial chordoma objectively confirmed by brachyury staining. A detailed case discussion and a review of the available literature on this rare clinicopathologic entity are provided.