Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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December 29, 2022
Intramedullary Spinal Cord Metastasis (ISCM) from Renal Cell Carcinoma
- Background:
- Intramedullary spinal cord metastases are rare, accounting for 0.1–2% of neoplastic CNS involvement. They have become more frequently seen with the increasing use of MR imaging and more effective cancer therapies.
- Lung cancer is the most common ISCM source, followed by breast cancer. Renal cell carcinoma corresponds solely to 4–9% of all ISCM.
- The primary malignancy has not always been diagnosed at the time of imaging.
- Prompt identification and appropriate intervention are urgent to prevent neurologic deficits and inappropriate treatment.
- Clinical Presentation:
- ISCM is often associated with rapid deterioration of neurologic function and devastating outcomes.
- Motor deficit is the most common symptom, either weakness or paraparesis. Back pain, paresthesias, and bladder or bowel dysfunction are also common, depending on the tumor location.
- Key Diagnostic Features:
- May arise anywhere in the spinal cord but more frequently occurs in the cervical cord followed by the thoracic cord.
- Usually single lesions, but multiple lesions are seen in 7% of patients.
- Almost all enhance and have associated extensive spinal cord edema. Intratumoral hemorrhage and cystic/necrotic changes are rare.
- Additional metastases of the primary tumor are extremely common.
- Differential Diagnoses:
- Primary spinal cord lesions, including ependymoma, astrocytoma, and hemangioblastoma: The "rim" (a more intense thin rim of peripheral enhancement around an enhancing lesion) and "flame" (an ill-defined flame-shaped region of enhancement at its superior and/or inferior margins) signs are common in ISCM and rare in primary spinal cord masses.
- Inflammatory lesions: transverse myelitis (usually more extended length of cord involvement and variable contrast enhancement) or multiple sclerosis (usually multiple lesions, sometimes without contrast enhancement, and less prominent cord expansion and edema)
- Treatment:
- ISCM is associated with a poor prognosis. Radiation therapy has been used for symptom relief. However, conventional external RT has little effect on radioresistant tumors such as renal cell carcinoma. Stereotactic radiosurgery is a promising approach for limited, oligometastatic disease. Chemotherapy has little effect. It has been used for chemotherapy-sensitive tumors and as adjuvant therapy for radiotherapy or surgery. Steroid therapy can quickly relieve symptoms and delay neurologic deterioration without prolonging the patient's survival.
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