CNS tumor
Neuronal and mixed neuronal-glial tumors
Dysembryoplastic neuroepithelial tumor
Author: Eman Abdelzaher, M.D., Ph.D.
Topic Completed: 1 December 2013
Minor changes: 28 September 2020
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: Dysembryoplastic neuroepithelial tumor (DNET)
Table of Contents
Definition / general | Sites | Diagrams / tables | Clinical features | Radiology description | Radiology images | Case reports | Treatment | Prognosis | Gross description | Gross images | Microscopic (histologic) description | Cytology description | Cytology images | Immunohistochemistry | Electron microscopy description | Differential diagnosisCite this page: Abdelzaher E. Dysembryoplastic neuroepithelial tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cnstumorDNET.html. Accessed January 17th, 2021.
Definition / general
- Benign mixed glioneuronal neoplasm of children and young adults, characteristically associated with intractable partial seizures
- Corresponds to WHO grade I
- First described by Daumas-Duport in 1988 (Neurosurgery 1988;23:545)
- Incidence:
- 1.2% of all neuroepithelial tumors diagnosed in patients younger than 20 years (Arq Neuropsiquiatr 1998;56:232)
- 1 - 19% of surgical resections for epilepsy
- Age and sex:
- Children and young adults
- Usually < 20 years
- Males are more affected
Sites
- Supratentorial cerebral cortex (50% temporal lobe)
- Other sites, e.g. septum pellucidum, basal ganglia, brain stem, cerebellum
Diagrams / tables
Images hosted on other servers:
Dysembryoplastic neuroepithelial tumor (DNET)
Clinical features
- Chronic partial seizures in supratentorial tumors
- No progressive neurological deficit
Radiology description
- MRI:
- Cortical based
- Hyperintense on T2 "bubbly appearance"
- No edema or mass effect
- Enhancement (1/3 of cases): heterogeneous or multiple ring pattern
- CT:
- May show calcification, may scallop the inner table of the skull vault
Radiology images
Images hosted on other servers:
10 year old girl with seizure
Case reports
- 9 year old boy with headache, visual changes and an occipital mass (Arch Pathol Lab Med 2002;126:991)
- 31 year old woman with seizures, fatigue and attention deficits (University of Pittsburgh: Seizures, Fatigue and Attention Deficits)
- 36 year old woman with composite ganglioglioma and dysembryoplastic neuroepithelial tumor (Arch Pathol Lab Med 1999;123:247)
Treatment
- Gross total resection or even subtotal resection usually achieves stabilization and seizure control
Prognosis
- Benign with excellent prognosis even with subtotal resection
- Rare recurrence
- Anaplastic transformation is extremely rare
Gross description
- Multinodular cortical lesion
- Soft and gelatinous
Gross images
Images hosted on other servers:
Frontobasal surgical specimen
Microscopic (histologic) description
- Intracortical lesion
- Uniform oligodendroglioma-like cells in a mucin rich background
- Hallmark: specific glioneuronal elements (columns formed of axons lined by uniform oligodendroglioma-like cells) with intervening floating neurons (cortical neurons in mucin pools)
- Scattered astrocytes
- Cortical dysplasia in adjacent cortex
- Rare mitotic figures
- Histological types:
- Simple form: specific glioneuronal elements only
- Complex form: glial nodules (imparting the multinodular appearance) with internodular specific glioneuronal elements and adjacent cortical dysplasia
- Nonspecific form: controversial entity, no specific glioneuronal elements, resembles low grade glioma, diagnosed on clinicoradiological grounds
Cytology description
- Oligodendroglioma-like cells
- Cortical neurons
- Mucin rich background
- Floating neurons in clusters or intricate patterns or microcystic
- Also prominent extracellular mucin
- Compared to oligodendrogliomas, have larger nuclei, frequent nuclear indentation and multiple small nucleoli (vs. round nuclei with only occasional nucleoli in oligodendrogliomas)
- Also have eosinophilic granular bodies in background (Acta Cytol 2003;47:624), may have bipolar astrocytes, mild nuclear atypia, microcystic change
- Adjacent cortex may show cortical dysplasia with disturbed lamination and architectural disarray
- No / rare necrosis, no / rare endothelial proliferation, uncommon mitotic figures
Cytology images
Images hosted on other servers:
Smear preparations
Partially arranged as columnar structures
Fine neuritic processes
Immunohistochemistry
- Oligodendroglia-like cells: S100
- Neurons: NeuN, synaptophysin, neurofilament
- Glia: GFAP
- Mucin: Alcian blue
- Ki67: low
Electron microscopy description
- Oligodendroglial-like cells, elongated processes forming a neuropil-like structure and an expanded mucoid extracellular space (Folia Neuropathol 1999;37:167)
Differential diagnosis
- Ganglioglioma: macrocystic component, neoplastic neurons, reticulin rich stroma, perivascular lymphocytes
- Oligodendroglioma: nonenhancing, diffusely infiltrative, involves white matter with infiltration of cortex and perineuronal satellitosis, more polymorphic cells
- Pilocytic astrocytoma: biphasic pattern
- Rosette forming glioneuronal tumor: usually 4th ventricle, well formed, small synaptophysin+ rosettes
