Choroid plexus papilloma originating from the cerebrum parenchyma.

BACKGROUND: Choroid plexus papilloma (CPP) can develop at a primary intraparenchymal location completely unrelated to the ventricular system. Here, we present a case of CPP that was difficult to diagnose preoperatively.

CASE DESCRIPTION: Preoperative imaging and operative findings showed that the tumor originated entirely within the cerebrum parenchyma, with no connections between the tumor and the ventricular system. Histopathological examination of the tumor revealed a papillary structure with a single layer of well-differentiated columnar epithelium in the lesion. Furthermore, part of this lesion had infiltrated the cerebral parenchyma. Therefore, the tumor was diagnosed as CPP, and the diagnosis was confirmed by immunohistological examination.

CONCLUSIONS: CPP originating as intraparenchymal growths are extremely rare. Origins of extraventricular CCP are discussed in the context of the literature.