Would you describe this lesion as central, eccentric or exophytic in location?
This is a borderline case. Although the mass appears relatively central, there is significantly more 'normal' cord posteriorly and to the left of the lesion, with no normal tissue seen anteriorly. As such this is best thought of as eccentric, although not exophytic.
What are the two main differentials and which do you favour? Why?
Ependymoma and astrocytoma. The later (spinal astrocytoma) should be favoured as the mass appears to be eccentric, with heterogenous diffuse enhancement and no evidence of haemorrhage.
T2 hyperintense expansion of the thoracic cord is demonstrated. The main mass effect is centred between T5 and T8 but abnormal high T2 signal extends between T4 and T11. Postcontrast images demonstrate patchy irregular peripheral enhancement of this lesion, and central low intensity. No definite evidence of blood products/haemorrhage although some T2 hypointensity is seen. No further intramedullary lesion is identified.