This rosette consists of tumor cells collected around a blood vessel. It’s called a pseudorosette because the central structure isn’t part of the tumor. In the past, the term pseudorosette meant any rosette that didn’t have a truly empty lumen…but it seems that designation is kind of outdated. These rosettes are common in ependymomas, but you also see them in medulloblastoma, PNET, central neurocytomas, and glioblastomas.