At the time of imaging, the differential included meningioma, but this would be expected to show more intense and homogeneous enhancement. Central neurocytoma was also considered, as it is commonly found in the lateral ventricles near the foramen of Monro, with 'bubbly' cystic areas. However moderate to strong heterogenous enhancement would be expected.
Although subependymomas are typically described in the inferior fourth ventricle, they also occur in the lateral, third ventricles and spinal cord. They are most commonly small, although can become large as in this case. Variable enhancement is seen (typically none to mild), but marked enhancement is also a feature (more commonly in the fourth ventricle than lateral ventricles). The most common demographics is in middle-aged to elderly males. In general, the diagnosis should be considered in a hyperintense ventricular tumour with poor enhancement (other ventricular tumours enhance more prominently).
They are WHO grade I tumours.