A 2-year-old boy presents with persistent vomiting. Brain MRI shows an enhancing 4th ventricle lesion.   

Photomicrographs of a cytologic smear preparation and H&E sections are shown. 

What is your diagnosis?

A. Medulloblastoma 

B. Anaplastic ependymoma

C. Atypical teratoid/rhabdoid tumor

D. Intraventricular rhabdoid meningioma