The differential is essentially that of other choroid plexus tumors:
atypical choroid plexus papilloma: indistinguishable, but far less common
choroid plexus carcinoma: can be very difficult on imaging alone
almost exclusively found in young children heterogeneous contrast enhancement may show parenchymal invasion
choroid plexus metastases
When located in the posterior fossa in children (less common) other tumours to be considered include:
medulloblastoma
atypical teratoid/rhabdoid tumour (AT/RT)
ependymoma
In adults, and depending on location, consider:
exophytic glioma
Papillary ependymoma is a rare variant of ependymoma and often gives rise to confusion with choroid plexus papilloma because of topographic, light microscopic and ultrastructural similarities.