LAUSR

A 20-year-old male patient was admitted to the hospital because of a 3-month history of lumbosacral pain and constipation. Physical examination showed decreased superficial sensitivity in both lower extremities. Lumbosacral magnetic resonance imaging (MRI) showed an intraspinal lesion at the S1 level. T1-weighted enhanced MRI demonstrated a homogenous enhancement of the mass. In addition, the MRI also showed lumbar scoliosis, diastematomyelia at the L3–L4 level, and syringomyelia at the T12–L1 level (Fig 1). The low position of the medullary conus and the patient’s clinical symptoms suggested tethered cord syndrome. Computed tomographic 3-dimensional reconstruction demonstrated the bony mediastinum at the L3–L4 level (Fig 2). This series of imaging features complicated our preoperative diagnosis, and we considered the mass to be a neurogenic tumor such as a schwannoma, or a congenital tumor like a teratoma. The surgical procedure was complicated by the patient’s congenital spinal deformity. However, a new intraoperative discovery was made that the tumor grew from the medullary cone of the spinal cord, and the filum terminale attached to the superior end appeared to be its origin. It was a solid, gray–brown, elliptic, enveloped tumor with abundant blood supply. We carefully dissected the surrounding structures of the tumor and removed the mass en bloc; at the same time, the bony mediastinum was removed by electric drill, and the compressed spinal cord was fully