A 40-year-old male presents with progressive weakness and sensory changes in his upper limbs. MRI of the cervical spine reveals an intramedullary mass at C4-C5 level. The mass is T1 isointense, T2 hyperintense, shows heterogeneous enhancement, and is associated with a 'cap sign' (hemosiderin rim) at its poles and an associated syrinx. These features are most characteristic of which spinal cord tumor?

Explanation

Spinal ependymomas are the most common intramedullary tumors in adults. Characteristic MRI features include T1 isointensity, T2 hyperintensity, heterogeneous enhancement, and often a 'cap sign' (hemosiderin rim) at the superior and inferior poles due to chronic hemorrhage, which is highly suggestive. They are also frequently associated with a syrinx. Spinal astrocytomas are often more infiltrative, less well-defined, and less likely to have a 'cap sign.' Hemangioblastomas are typically highly vascular, often with a mural nodule and large associated syrinx, and flow voids. Schwannomas are extramedullary-intradural or foraminal tumors, not intramedullary.