Choroid Plexus Papilloma

Choroid plexus papillomas are low grade tumors that arise from the intraventricular CSF-producing choroid plexus. Here we see the transition from the round bland nuclei and ample pink cytoplasm of the normal choroid plexus epithelium (bottom of image) to the dysplastic columnar epithelium of the papilloma (top of image) featuring nuclear crowding and mitotic activity (arrowheads).