title: The diagnostic properties of frozen sections in suspected intracranial tumors: A study of 578 consecutive cases.
abstract: BACKGROUND
  Intraoperative frozen section (FS) diagnostics is an important diagnostic tool in neurosurgery, but agreement with final histopathology diagnoses may vary. In the present study we assess the diagnostic properties of intraoperative FSs in suspected intracranial tumors.
  
  
  METHODS
  Retrospective single-center review of consecutive patients with suspected intracranial brain tumors from January 2008 to December 2012. We included all cases were both an intraoperative FS and a formalin-fixed paraffin-embedded (FFPE) section had been acquired. Agreement with final diagnosis, sensitivity, specificity, and predictive values were explored. Time between date of surgery and first final diagnosis based on FFPE section, whether the patients had undergone previous brain surgery and/or prior cerebral radiotherapy were also registered.
  
  
  RESULTS
  Agreement between FS diagnoses and final FFPE section diagnoses was seen in 504/558 (90.3%), while there was lack of agreement in 54/558 (9.7%). In 20 cases, agreement was not classifiable. Agreement was lower in low-grade gliomas (82.5%) than in high-grade gliomas (93.2%). Agreement between FS and FFPE was significantly higher in primary operations (92.1%) than in re-do operations (81.5%) (P = 0.001). Sensitivity of FS ranged from 30.8% in lymphomas to 94.6% in meningiomas.
  
  
  CONCLUSIONS
  Intraoperative FS diagnoses demonstrate high diagnostic accuracy. However, agreement varies among histopathological entities and is lower in low-grade tumors than in high-grade tumors. Sensitivity for diagnosing CNS lymphomas is low. A variable degree of reservation is always necessary when interpreting and communicating FS diagnoses.
authors.affiliation: Medical Faculty, Norwegian University of Science and Techology, Trondheim, Norway.
authors.forename: Kathrine
authors.initials: K
authors.lastname: Tofte
authors.affiliation: Medical Faculty, Norwegian University of Science and Techology, Trondheim, Norway.
authors.forename: Cathrine
authors.initials: C
authors.lastname: Berger
authors.affiliation: Department of Laboratory Medicine, Childeren's and Women's Health, Norwegian University of Science and Technology, Trondheim, Norway ; Department of Pathology and Medical Genetics, St. Olavs University Hospital, Trondheim, Norway.
authors.forename: Sverre Helge
authors.initials: SH
authors.lastname: Torp
authors.affiliation: Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway ; Department of Neurosurgery, St. Olavs University Hospital, Trondheim, Norway ; National Centre for Ultrasound and Image Guided Therapy, St. Olavs University Hospital, Trondheim, Norway.
authors.forename: Ole
authors.initials: O
authors.lastname: Solheim
keywords: Brain tumor; frozen section; histology; sensitivity; specificity