title: Choroid plexus papilloma originating from the cerebrum parenchyma.
abstract: 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.
  
  
  METHODS
  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.
authors: Department of Neurosurgery, Tokai University School of Medicine, Isehara, Kanagawa 259-1193, Japan.
authors: Masaaki
authors: M
authors: Imai
authors: Jiro
authors: J
authors: Tominaga
authors: Mitsunori
authors: M
authors: Matsumae