What are the key imaging and clinical features of spinal cord ependymomas, and how do they differ between cellular and myxopapillary types?

Spinal cord ependymomas are the most common intramedullary spinal tumors in adults, with a peak incidence in the fourth decade and a male predominance. They are divided into cellular (intramedullary) and myxopapillary (filum terminale) types. On MRI, they typically show low T1 and high T2 signal with variable enhancement and are expansile. Cellular ependymomas often present with a central location and may cause hemorrhage, while myxopapillary ependymomas are more common in the lumbosacral region. Increased incidence is noted in neurofibromatosis type 2. Key diagnostic features include a 'cap sign' (hemosiderin cap) and potential cyst formation. Common pitfalls include misidentification as astrocytomas, which are less likely to have a central location or hemorrhage.