Symptomatic child case of subependymoma in the fourth ventricle without hydrocephalus.

We report a rare child case of symptomatic subependymoma in the fourth ventricle without hydrocephalus. The upper half of the tumor was demonstrated as a non-enhancing isodense mass with punctate calcification on CT, whereas the lower portion showed slightly irregular ring-like enhancement with a central hypodense area. The tumor was heterogeneously hyperintense on T2-weighted magnetic resonance (MR) images. When scanned with a T1-weighted sequence, the upper portion of the tumor was isointense to brain, but the lower portion was hypointense. However, using Gd-enhanced T1-weighted imaging, such as in postcontrast CT, the upper portion did not enhance, whereas the lower portion revealed similar ring-like enhancement, which was suggestive of necrosis. To further confirm the nature of the tumor, a diffusion-weighted imaging study with echo-planar technique was performed, and it indicated the solid nature of the tumor, which was confirmed histopathologically.