MRI
Sagittal T2
Axial T2
Sagittal T1
Axial T1
Sagittal T1 C+ fat sat
Axial T1 C+
Within the conus (definitely intramedullary) is there a predominantly cystic lesion that occupies the entire canal. It is predominantly cystic (high T2) with some heterogeneous signal posterior inferiorly including areas of high intrinsic T1 signal that appear to drop signal on fat-saturated post-contrast sequences suggesting the presence of fat. There is likely a small heterogeneous component of enhancing soft tissue posteriorly on the right. The film arises from the lower apex of the lesion, with cauda equina displaced a peripherally.
This is an isolated lesion. The remainder of the imaged cord, the cauda equina, and the thecal cul-de-sac appear unremarkable.
Incidental retro-aortic renal vein.
Conclusion:
The lesion is definitely intramedullary, within the conus, and is predominantly cystic, with a heterogeneous solid component including what appears to be foci of fat. These features strongly favour a cystic teratoma of the conus.