title: Not all 1p/19q non-codeleted oligodendroglial tumors are astrocytic.
abstract: Although 1p/19q codeletion is the genetic hallmark defining oligodendrogliomas, approximately 30-40% of oligodendroglial tumors have intact 1p/19q in the literature and they demonstrate a worse prognosis. This group of 1p/19q intact oligodendroglial tumors is frequently suggested to be astrocytic in nature with TP53 and ATRX mutations but actually remains under-investigated. In the present study, we provided evidence that not all 1p/19q intact oligodendroglial tumors are astrocytic through histologic and molecular approaches. We examined 1p/19q status by FISH in a large cohort of 337 oligodendroglial tumors and identified 39.8% lacking 1p/19q codeletion which was independently associated with poor prognosis. Among this 1p/19q intact oligodendroglial tumor cohort, 58 cases demonstrated classic oligodendroglial histology which showed older patient age, better prognosis, association with grade III histology, PDGFRA expression, TERTp mutation, as well as frequent IDH mutation. More than half of the 1p/19q intact oligodendroglial tumors showed lack of astrocytic defining markers, p53 expression and ATRX loss. TP53 mutational analysis was additionally conducted in 45 cases of the 1p/19q intact oligodendroglial tumors. Wild-type TP53 was detected in 71.1% of cases which was associated with classic oligodendroglial histology. Importantly, IDH and TERTp co-occurred in 75% of 1p/19q intact, TP53 wild-type oligodendrogliomas, highlighting the potential of the co-mutations in assisting diagnosis of oligodendrogliomas in tumors with clear cell morphology and non-codeleted 1p/19q status. In summary, our study demonstrated that not all 1p/19q intact oligodendroglial tumors are astrocytic and co-evaluation of IDH and TERTp mutation could potentially serve as an adjunct for diagnosing 1p/19q intact oligodendrogliomas.
authors.affiliation: Department of Anatomical and Cellular Pathology, Chinese University of Hong Kong, Hong Kong, China.|Shenzhen Research Institute, Chinese University of Hong Kong, Hong Kong, China.|Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China.
authors.forename: Yan-Xi
authors.initials: YX
authors.lastname: Li
authors.affiliation: Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China.
authors.forename: Zhifeng
authors.initials: Z
authors.lastname: Shi
authors.affiliation: Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China.
authors.forename: Abudumijiti
authors.initials: A
authors.lastname: Aibaidula
authors.affiliation: Department of Neuropathology, Huashan Hospital, Fudan University, Shanghai, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China.
authors.forename: Qisheng
authors.initials: Q
authors.lastname: Tang
authors.affiliation: Department of Anatomical and Cellular Pathology, Chinese University of Hong Kong, Hong Kong, China.|Shenzhen Research Institute, Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Kay Ka-Wai
authors.initials: KK
authors.lastname: Li
authors.affiliation: Department of Anatomical and Cellular Pathology, Chinese University of Hong Kong, Hong Kong, China.|Shenzhen Research Institute, Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Nellie Yuk-Fei
authors.initials: NY
authors.lastname: Chung
authors.affiliation: Neurosurgery Division, Department of Surgery, Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Danny Tat-Ming
authors.initials: DT
authors.lastname: Chan
authors.affiliation: Neurosurgery Division, Department of Surgery, Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Wai Sang
authors.initials: WS
authors.lastname: Poon
authors.affiliation: Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Mao
authors.affiliation: Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China.
authors.forename: Jinsong
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China.
authors.forename: Liangfu
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Anatomical and Cellular Pathology, Chinese University of Hong Kong, Hong Kong, China.|Shenzhen Research Institute, Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Aden Ka-Yin
authors.initials: AK
authors.lastname: Chan
authors.affiliation: Department of Anatomical and Cellular Pathology, Chinese University of Hong Kong, Hong Kong, China.|Shenzhen Research Institute, Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Ho-Keung
authors.initials: HK
authors.lastname: Ng
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001253:Astrocytes / Q000502:physiology*; D001932:Brain Neoplasms / Q000235:genetics / Q000401:mortality / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D002872:Chromosome Deletion; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics*; D002888:Chromosomes, Human, Pair 19 / Q000235:genetics*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007521:Isocitrate Dehydrogenase / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D009837:Oligodendroglioma / Q000235:genetics / Q000401:mortality / Q000473:pathology*; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000378:metabolism; D016019:Survival Analysis; D019098:Telomerase / Q000235:genetics; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D000075924:X-linked Nuclear Protein / Q000235:genetics; D055815:Young Adult
chemical_list: D016159:Tumor Suppressor Protein p53; D007521:Isocitrate Dehydrogenase; D020796:Receptor, Platelet-Derived Growth Factor alpha; C509186:TERT protein, human; D019098:Telomerase; D000075924:X-linked Nuclear Protein
keywords: IDH; Pathology Section; TERT; intact 1p/19q; oligodendroglial tumors