title: Globular glial tauopathies (GGT): consensus recommendations.
abstract: Recent studies have highlighted a group of 4-repeat (4R) tauopathies that are characterised neuropathologically by widespread, globular glial inclusions (GGIs). Tau immunohistochemistry reveals 4R immunoreactive globular oligodendroglial and astrocytic inclusions and the latter are predominantly negative for Gallyas silver staining. These cases are associated with a range of clinical presentations, which correlate with the severity and distribution of underlying tau pathology and neurodegeneration. Their heterogeneous clinicopathological features combined with their rarity and under-recognition have led to cases characterised by GGIs being described in the literature using various and redundant terminologies. In this report, a group of neuropathologists form a consensus on the terminology and classification of cases with GGIs. After studying microscopic images from previously reported cases with suspected GGIs (n = 22), this panel of neuropathologists with extensive experience in the diagnosis of neurodegenerative diseases and a documented record of previous experience with at least one case with GGIs, agreed that (1) GGIs were present in all the cases reviewed; (2) the morphology of globular astrocytic inclusions was different to tufted astrocytes and finally that (3) the cases represented a number of different neuropathological subtypes. They also agreed that the different morphological subtypes are likely to be part of a spectrum of a distinct disease entity, for which they recommend that the overarching term globular glial tauopathy (GGT) should be used. Type I cases typically present with frontotemporal dementia, which correlates with the fronto-temporal distribution of pathology. Type II cases are characterised by pyramidal features reflecting motor cortex involvement and corticospinal tract degeneration. Type III cases can present with a combination of frontotemporal dementia and motor neuron disease with fronto-temporal cortex, motor cortex and corticospinal tract being severely affected. Extrapyramidal features can be present in Type II and III cases and significant degeneration of the white matter is a feature of all GGT subtypes. Improved detection and classification will be necessary for the establishment of neuropathological and clinical diagnostic research criteria in the future.
authors.affiliation: Department of Molecular Neuroscience, Queen Square Brain Bank, Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
authors.forename: Zeshan
authors.initials: Z
authors.lastname: Ahmed
authors.affiliation: Department of Pathology, Northwestern Alzheimer Disease Center, Northwestern Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Eileen H
authors.initials: EH
authors.lastname: Bigio
authors.affiliation: Institute of Neurology, Medical University of Vienna, Vienna, Austria.
authors.forename: Herbert
authors.initials: H
authors.lastname: Budka
authors.affiliation: Mayo Clinic, Jacksonville, FL, usA.
authors.forename: Dennis W
authors.initials: DW
authors.lastname: Dickson
authors.affiliation: Institute of Neuropathology, University Hospital Bellvitge, University of Barcelona, CIBERNED, Hospitalet de LLobregat, Spain.
authors.forename: Isidro
authors.initials: I
authors.lastname: Ferrer
authors.affiliation: Department of Pathology and Laboratory Medicine, Indiana Alzheimer Disease Center, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Bernardino
authors.initials: B
authors.lastname: Ghetti
authors.affiliation: Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Giaccone
authors.affiliation: Department of Pathology, Alzheimer's Disease Center, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Kimmo J
authors.initials: KJ
authors.lastname: Hatanpaa
authors.affiliation: Department of Molecular Neuroscience, Queen Square Brain Bank, Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
authors.forename: Janice L
authors.initials: JL
authors.lastname: Holton
authors.affiliation: Mayo Clinic, Rochester, MN, USA.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Josephs
authors.affiliation: University of Rochester, School of Medicine and Dentistry, Rochester, NY, USA.
authors.forename: James
authors.initials: J
authors.lastname: Powers
authors.affiliation: Department of Pathology and Laboratory Medicine, Indiana Alzheimer Disease Center, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Spina
authors.affiliation: Department of Pathology, Brain Research Institute, Niigata University, Niigata, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Department of Pathology, Alzheimer's Disease Center, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Charles L
authors.initials: CL
authors.lastname: White
authors.affiliation: Department of Molecular Neuroscience, Queen Square Brain Bank, Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
authors.forename: Tamas
authors.initials: T
authors.lastname: Revesz
authors.affiliation: Institute of Neurology, Medical University of Vienna, Vienna, Austria.
authors.forename: Gabor G
authors.initials: GG
authors.lastname: Kovacs
mesh_terms: D001253:Astrocytes / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D002479:Inclusion Bodies / Q000473:pathology; D019636:Neurodegenerative Diseases / Q000473:pathology; D009457:Neuroglia / Q000473:pathology*; D016622:Silver Staining; D024801:Tauopathies / Q000145:classification / Q000473:pathology*; D009626:Terminology as Topic; D016875:tau Proteins / Q000737:chemistry
chemical_list: D016875:tau Proteins