FISH analysis of brain smears obtained at intraoperative diagnosis - An accurate and fast method to detect 1p/19q-codeletion in gliomas

Joanne Brown; Sally Byatt; Tayyaba Khan; Luke St Heaps; Mark Dexter; Najmun Nahar; Mark Wong; King Tan; Winny Varikatt

doi:10.1016/j.jocn.2021.07.043

FISH analysis of brain smears obtained at intraoperative diagnosis - An accurate and fast method to detect 1p/19q-codeletion in gliomas

J Clin Neurosci. 2021 Oct:92:115-119. doi: 10.1016/j.jocn.2021.07.043. Epub 2021 Aug 7.

Authors

Joanne Brown¹, Sally Byatt¹, Tayyaba Khan¹, Luke St Heaps², Mark Dexter³, Najmun Nahar⁴, Mark Wong⁵, King Tan⁶, Winny Varikatt⁷

Affiliations

¹ Tissue Pathology and Diagnostic Oncology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Darcy Rd, Westmead, NSW 2145, Australia.
² FISH Section, Cytogenetics Department, Children's Hospital at Westmead, Hawkesbury Rd, Westmead, NSW 2145, Australia.
³ Department of Neurosurgery, Westmead Hospital, Darcy Rd, Westmead, NSW 2145, Australia; Sydney Medical School, University of Sydney, NSW 2006, Australia.
⁴ Department of Radiation Oncology, Westmead Hospital, Darcy Rd, Westmead, NSW 2145, Australia.
⁵ Department of Medical Oncology, Westmead Hospital, Darcy Rd, Westmead, NSW 2145, Australia; Sydney Medical School, University of Sydney, NSW 2006, Australia.
⁶ Douglass Hanly Moir, Macquarie Park, NSW 2113, Australia; Sydney Medical School, University of Sydney, NSW 2006, Australia.
⁷ Tissue Pathology and Diagnostic Oncology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Darcy Rd, Westmead, NSW 2145, Australia; Sydney Medical School, University of Sydney, NSW 2006, Australia. Electronic address: winny.varikatt@health.nsw.gov.au.

PMID: 34509237
DOI: 10.1016/j.jocn.2021.07.043

Abstract

The importance of molecular testing of gliomas is highlighted in the 2016 revised 4th edition of the WHO Classification of Tumours of the Central Nervous System, which applies an integrated diagnosis of histological and molecular features. In this classification system, oligodendrogliomas (ODG) are defined as IDH-mutant and 1p/19q-codeleted. Fluorescence in situ hybridization (FISH) analysis of formalin-fixed paraffin-embedded (FFPE) tissue is a standard method of determining 1p/19q-codeletion. However, it has several disadvantages, including requiring lengthy pretreatment, truncation artefact and lack of on-site access in many centers. In an effort to address these issues, we analysed FISH performed on smears obtained at intraoperative frozen section on 51 gliomas and compared this to FISH performed on subsequent FFPE sections. Four cases were excluded due to uninterpretable FISH results. Of the remaining 47 cases, 17 were concordant for 1p/19q-codeletion, 29 were concordant for lack of 1p/19q-codeletion, and 1 was discordant with 1p/19q-codeletion found on FFPE tissue but not on intraoperative smears. The discordant case was most likely due to sampling error, as the frozen section had not shown definite tumor. The FISH results on intraoperative smears were received within 24-48 h after the sample was collected, compared with 3-4 days for FFPE tissue. FISH on smears obtained at intraoperative frozen section is an accurate and fast method for determining 1p/19q-codeletion.

Keywords: 1p19q; FISH; Fluorescence in situ hybridization; Fresh brain smears; Glioma; Oigodendroglioma.

MeSH terms

Brain
Brain Neoplasms* / diagnosis
Brain Neoplasms* / genetics
Brain Neoplasms* / surgery
Glioma* / diagnosis
Glioma* / genetics
Glioma* / surgery
Humans
In Situ Hybridization, Fluorescence
Isocitrate Dehydrogenase

Substances

Isocitrate Dehydrogenase