Oligodendroglial tumors diagnosis [Neurosurgery Wiki]

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====== Oligodendroglial tumors diagnosis ======

Oligodendroglioma is diagnosed based on histology of infiltrating glioma together with [[IDH-mutation]] AND [[1p/19q co-deletion]].

They need molecular work up with readily available techniques like [[immunohistochemistry]] and [[Fluorescence in situ hybridization]]
((Lavanya G, Uppin MS, Alugolu R, Bhattacharjee S, Saradhi MV, Yeramneni VK. Clinical Profile, Pathology, and Molecular Typing of Gliomas with Oligodendroglial Morphology: A Single Institutional Experience. Neurol India. 2022 May-Jun;70(3):1020-1024. doi: 10.4103/0028-3886.349641. PMID: 35864633.))


===== Imaging =====

[[Oligodendroglioma Magnetic resonance imaging]]

Calcifications: seen in 28–60% of ODGs on plain radiographs
((Mork SJ, Lindegaard KF, Halvorsen TB, et al. Oligodendroglioma: Incidence and Biological Behavior in a Defined Population. J Neurosurg. 1985; 63:881–889)),
and on 90% of CTs.




A [[Computed Tomography]] (CT) or [[Magnetic Resonance Imaging]] (MRI) scan is necessary to characterize the anatomy of this [[tumor]] (size, location, heter/homogeneity). However, final [[diagnosis]] of this tumor, like most tumors, relies on histopathologic examination ([[biopsy]] examination).

===== Histology =====

Tumors show moderate cellularity. Cells with monotonous round nuclei (often in cellular sheets) with an eccentric rim of eosinophilic cytoplasm lacking obvious cell processes are the most consistent features
((Fortin D, Cairncross GJ, Hammond RR. Oligodendroglioma: An Appraisal of Recent Data Pertaining to Diagnosis and Treatment. Neurosurgery. 1999; 45:1279–1291)).

73% of tumors have microscopic calcifications
((Roberts M, German W. A Long Term Study of Patients with Oligodendrogliomas. J Neurosurg. 1966; 24:697–700)).

Isolated tumor cells consistently penetrate largely intact parenchyma; an associated solid tumor component may or may not be present.

When a solid portion is present, permanent (paraffin) pathology demonstrates lucent perinuclear halos, giving a “fried egg” appearance (actually an artifact of formalin fixation, which is not present on frozen section and may make diagnosis difficult on frozen). A “chicken-wire” vascular pattern has also been described.
((Coons SW, Johnson PC, Pearl DK, et al. The
Prognostic Significance of Ki-67 Labeling Indices for Oligodendrogliomas. Neurosurgery. 1997; 41: 878–885)).
These features are variable.

Nuclear atypia and an occasional mitotic figure are compatible with the diagnosis. Compare to WHO grade III anaplastic oligodendroglioma, IDH-mutant 1p/19q codeleted.

16% of hemispheric ODGs are cystic58 (cysts form from the coalescence of microcysts from microhemorrhages, unlike astrocytomas, which actively secrete fluid).
GFAP staining: Since most ODGs contain microtubules instead of glial filaments,
ODGs usually do not stain for GFAP, although some do. In mixed gliomas, the astrocytic component may stain for GFAP.
----
The purpose of a study was to assess the value of [[dynamic susceptibility contrast MRI imaging]] (DSC-MRI) and [[diffusion weighted imaging]] (DWI) to characterize [[oligodendroglioma]]s and to distinguish them from [[astrocytoma]]s.

Seventy-one adult patients with untreated WHO grade II and grade III diffuse infiltrating gliomas and known 1p/19q codeletion status were retrospectively identified and analyzed using [[relative cerebral blood volume]] ([[rCBV]]) and [[apparent diffusion coefficient]] ([[ADC]]) maps based on whole-tumor volume histograms. The [[Mann Whitney U test]] and [[logistic regression]] were used to assess the ability of rCBV and ADC to differentiate between [[oligodendroglioma]]s and [[astrocytoma]]s both independently, but also related to the WHO grade. Prediction performance was evaluated in leave-one-out cross-validation (LOOCV).

Oligodendrogliomas showed significantly higher microvascularity (higher rCBVMean ≥ 0.80, p = 0.013) and higher vascular heterogeneity (lower rCBVPeak ≤ 0.044, p = 0.015) than astrocytomas. [[Diffuse glioma]]s with higher cellular density (lower ADCMean ≤ 1094 × 10-6 mm2/s, p = 0.009) were more likely to be oligodendrogliomas than astrocytomas. Histogram analysis of rCBV and ADC was able to differentiate between diffuse astrocytomas (WHO grade II) and [[anaplastic astrocytoma]]s (WHO grade III).

Histogram-derived rCBV and [[ADC]] parameter may be used as biomarkers for identification of oligodendrogliomas and may help characterize [[diffuse glioma]]s based upon their genetic characteristics
((Latysheva A, Emblem KE, Brandal P, Vik-Mo EO, Pahnke J, Røysland K, Hald JK,
Server A. Dynamic susceptibility contrast and diffusion MR imaging identify
oligodendroglioma as defined by the 2016 WHO classification for brain tumors:
histogram analysis approach. Neuroradiology. 2019 Feb 2. doi:
10.1007/s00234-019-02173-5. [Epub ahead of print] PubMed PMID: 30712139.
)).



===== Oligodendroglioma 1p/19q co-deletion =====

[[Oligodendroglioma 1p/19q co-deletion]]