Choroid plexus papilloma with neuropil-like islands.

Choroid plexus papilloma may display unusual histologic features, but the presence of neuronal differentiation at the light microscopic level has not yet been described. We thus report a choroid plexus papilloma with neuropil-like islands located within the lateral ventricle of an 11-year-old girl. The absence of atypical histologic features associated with recurrence (particularly increased mitotic activity) and recurrence-free follow-up upon gross total resection are compatible with a diagnosis of choroid plexus papilloma (WHO grade I). This case further emphasizes the capacity of choroid plexus tumor cells toward neuronal differentiation, and expands the spectrum of tumors, which may contain neuropil-like islands.