Secondary Chondrosarcoma Arising from the Proximal Fibula Presenting as Sciatica

INTRODUCTION: Secondary chondrosarcoma is a rare entity arising from a pre-existing cartilaginous lesion. Transformation of an osteochondroma to a chondrosarcoma occurs in <1% of cases. Sciatica is a common problem that can cause significant pain, weakness, and numbness. CASE REPORT: A 36-year-old male presented to the Orthopedic Oncology Service after being treated for sciatica for 3 years. Magnetic resonance imaging of the lumbar spine demonstrated degenerative disc disease with mild inferior foraminal narrowing at L5-S1. He had undergone multiple epidural steroid injections without improvement in his symptoms. A chondrosarcoma encasing the peroneal nerve was found arising from an underlying osteochondroma in the proximal fibula. The patient underwent resection of the tumor which included resection of the peroneal nerve. Five years after resection, the patient is disease free and uses an ankle-foot orthosis for ambulation. CONCLUSION: This case demonstrates the importance of evaluating a patient with peripheral nerve symptoms for a lesion within the involved extremity along the entire length of the nerve. Extraspinal lesions can compress peripheral nerves and cause radicular symptoms. Timely treatment is important to prevent malignant transformation or worsening of the tumor as well as to provide better functional outcome.