title: Diagnostic Significance of Cellular Neuroglial Tissue in Ovarian Immature Teratoma.
abstract: BACKGROUND
  Immature teratoma (IT) is a tumor containing immature neuroectodermal tissue, primarily in the form of neuroepithelial tubules. However, the diagnosis of tumors containing only cellular neuroglial tissue (CNT) without distinct neuroepithelial tubules is often difficult, since the histological characteristics of immature neuroectodermal tissues remain unclear. Here, we examined the significance of CNT and tried to define immature neuroectodermal tissues by comparing the histological features of neuroglial tissues between mature teratoma (MT) and IT.
  
  
  METHODS
  The histological features of neuroglial tissue, including the cellularity, border between the neuroglial and adjacent tissues, cellular composition, mitotic index, Ki-67 proliferation rate, presence or absence of tissue necrosis, vascularity, and endothelial hyperplasia, were compared between 91 MT and 35 IT cases.
  
  
  RESULTS
  CNTs with a cellularity grade of ≥ 2 were observed in 96% of IT cases and 4% of MT cases (p < .001); however, CNT with a cellularity grade of 3 in MT cases was confined to the histologically distinct granular layer of mature cerebellar tissue. Moreover, CNT in IT exhibited significantly higher rates of Ki-67 proliferation, mitoses, and necrosis than those in MT (p < .001). Furthermore, an infiltrative border of neuroglial tissue and glomeruloid endothelial hyperplasia were significantly more frequent in IT cases than in MT cases (p < .001).
  
  
  CONCLUSIONS
  Our results suggest that if CNT with a cellularity grade of ≥ 2 is not a component of cerebellar tissue, such cases should be diagnosed as IT containing immature neuroectodermal tissue, particularly if they exhibit an infiltrative border, mitoses, necrosis, and increased Ki-67 proliferation.
authors.affiliation: Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Yun
authors.initials: Y
authors.lastname: Chai
authors.affiliation: Department of Pathology, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea.
authors.forename: Chang Gok
authors.initials: CG
authors.lastname: Woo
authors.affiliation: Department of Pathology, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea.
authors.forename: Joo-Young
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Chong Jai
authors.initials: CJ
authors.lastname: Kim
authors.affiliation: Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Shin Kwang
authors.initials: SK
authors.lastname: Khang
authors.affiliation: Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jiyoon
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: In Ah
authors.initials: IA
authors.lastname: Park
authors.affiliation: Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Eun Na
authors.initials: EN
authors.lastname: Kim
authors.affiliation: Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Kyu-Rae
authors.initials: KR
authors.lastname: Kim
keywords: Immature teratoma; Ki-67; Neuroectodermal; Neuroepithelium; Neuroglia; Ovary