Intramedullary and Extramedullary Thoracic Spinal Lipomas Without Spinal Dysraphism: Clinical Presentation and Surgical Management

BACKGROUND: Intradural intramedullary lipomas without dysraphism are rare tumors. Although they appear extramedullary on imaging, they invade into the intramedullary substance of the spinal cord. We present 2 cases and discuss their clinical presentation, radiologic findings, and surgical management. CASE DESCRIPTION: Case 1 is a 21-year-old woman who presented with upper back pain from recurrent lipoma. She had undergone partial excision in 2008 at an outside hospital. Physical examination revealed full strength but hyperreflexia in the legs. Magnetic resonance imaging (MRI) revealed a recurrent thoracic spinal tumor with spinal cord compression. Surgery was performed, and it was found that the tumor was both extramedullary and intramedullary, with an obscure delineation between tumor and cord. Subtotal excision was performed, and the patient remained neurologically intact. Case 2 is a 47-year-old woman who presented with leg weakness, difficulty in walking, and foot drop. Physical examination revealed 4/5 in the lower extremities. MRI demonstrated a spinal lipoma with thoracic cord compression. Even though the tumor appeared to be an extramedullary lesion by MRI, intraoperatively, the tumor became intramedullary with loss of distinction between the spinal cord and tumor. Subtotal excision was performed, and the patient regained her strength to 5/5 postoperatively. CONCLUSIONS: Intramedullary thoracic spinal lipomas without spinal dysraphism are rare. Although these tumors may appear completely extramedullary on imaging, extreme care should be taken during surgery because the lesions eventually become intramedullary, intercalating within the substance of the spinal cord, precluding gross total resection.