title: Anaplastic oligodendroglioma arising from the brain stem and featuring 1p/19q co-deletion.
abstract: With respect to localization, oligodendrogliomas are characterized by a marked preponderance of the cerebral hemispheres. Outside these typical sites, any tumor histopathologically reminiscent of oligodendroglioma a priori is likely to represent one of its morphological mimics, including clear cell ependymoma, neurocytoma, pilocytic astrocytoma or glioneuronal tumors. This is particularly relevant as several of the latter are in principle curable by surgery. Among extrahemispherical sites, bona fide oligodendroglioma - as characterized by loss of heterozygosity (LOH) of chromosome arms 1p and 19q - so far has not been documented to occur in the brain stem. Here, we report the case of a 55-year-old female patient with an anaplastic oligodendroglioma (WHO grade III) of the brain stem and cerebellum diagnosed by stereotactic biopsy and featuring combined LOH of 1p and 19q. A morphological peculiarity was a population of interspersed tumor giant cells, a phenomenon that has been referred to as polymorphous oligodendroglioma. Our findings confirm the notion that - although very infrequently - true oligodendrogliomas do occur in the infratentorial compartment.
authors.affiliation: Institute of Pathology, University of Bern, Bern, Switzerland.
authors.forename: Ekkehard
authors.initials: E
authors.lastname: Hewer
authors.forename: Jürgen
authors.initials: J
authors.lastname: Beck
authors.forename: Erik
authors.initials: E
authors.lastname: Vassella
authors.forename: Istvan
authors.initials: I
authors.lastname: Vajtai
mesh_terms: D020295:Brain Stem Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D002872:Chromosome Deletion; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics*; D002888:Chromosomes, Human, Pair 19 / Q000235:genetics*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009837:Oligodendroglioma / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology
keywords: brain stem; cerebellum; differential diagnosis; loss of heterozygosity; oligodendroglioma