CNS & pituitary tumors

Gliomas, glioneuronal tumors, and neuronal tumors

Neuronal and mixed neuronal-glial tumors

Dysembryoplastic neuroepithelial tumor


Editorial Board Member: Meaghan Morris, M.D., Ph.D.
Deputy Editor-in-Chief: Chunyu Cai, M.D., Ph.D.
Chris Dampier, M.D.
P.J. Cimino, M.D., Ph.D.

Last author update: 6 December 2022
Last staff update: 6 December 2022

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PubMed Search: Dysembryoplastic neuroepithelial tumor (DNET)

Chris Dampier, M.D.
P.J. Cimino, M.D., Ph.D.
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Cite this page: Dampier C, Cimino PJ. Dysembryoplastic neuroepithelial tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cnstumorDNET.html. Accessed March 28th, 2024.
Definition / general
  • Cortex based glioneuronal neoplasm that is often located in the mesial temporal lobe of adolescents and young adults and associated with medically refractory epilepsy, usually with activating mutations of FGFR1, CNS WHO grade 1 (Neurosurgery 1988;23:545)
Essential features
Terminology
  • Dysembryoplastic neuroepithelial tumor
  • Simple dysembryoplastic neuroepithelial tumor
  • Complex dysembryoplastic neuroepithelial tumor
ICD coding
  • ICD-O: 9413/0 - dysembryoplastic neuroepithelial tumor
  • ICD-11: 2A00.21 - mixed neuronal glial tumors
  • ICD-11: XH0H76 - dysembryoplastic neuroepithelial tumor
Epidemiology
Sites
Pathophysiology
  • Activating alteration in FGFR1 (receptor tyrosine kinase) > activation of MAPK pathway > dysregulated cell growth, proliferation and differentiation (Acta Neuropathol 2016;131:847)
Etiology
Diagrams / tables

Images hosted on other servers:

Relative distribution of LEATs

Proposed modification of LEAT classification

Nodular appearing neoplasm

Clinical features
Diagnosis
  • Cortical glioneuronal tumor with presence of specific glioneuronal component
  • FGFR1 alteration or DNA methylation profile can help in challenging cases
  • Preferable to make diagnosis in context of early onset focal epilepsy
Radiology description
Radiology images

Images hosted on other servers:

Representative imaging features in adolescent

Typical imaging features

10 year old girl with seizure

Prognostic factors
Case reports
Treatment
Clinical images

Images hosted on other servers:

Surgical resection of epileptogenic tumor

Gross description
  • Usually poorly demarcated (Epileptic Disord 2002;4:99)
  • Located predominantly in gray matter and subcortical white matter
  • May contain solid, mucoid or cystic components
Gross images

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Frontobasal surgical specimen

Microscopic (histologic) description
  • Growth pattern
  • Pathognomonic appearance
    • Bundles of axons lined by small oligodendroglia-like cells form columns oriented perpendicularly to the cortical surface with intervening cytologically normal neurons floating in a myxoid matrix (Neurosurgery 1988;23:545)
  • Absence of the following:
    • Dysplastic ganglion-like cells
    • High cellularity
    • Necrosis
    • Perivascular lymphoid infiltrates
    • Eosinophilic granular bodies
  • Simple form
    • Pathognomonic component alone
  • Complex form
Microscopic (histologic) images

Contributed by P.J. Cimino, M.D., Ph.D. and Chris Dampier, M.D.
Nodular growth pattern

Nodular growth pattern

Specific glioneuronal (pathognomonic) component

Specific glioneuronal (pathognomonic) component

Floating neuron

Floating neuron

Cystic component

Cystic component

GFAP

GFAP

IDH1 p.R132H

IDH1 p.R132H

Cytology description
  • Smear preparation (alcohol fixed, H&E stained) (Acta Cytol 2022;66:142)
    • Uniform round cells
    • Mucinous and fibrillary background
Cytology images

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Smear preparations

Partially arranged as columnar structures

Fine neuritic processes

Positive stains
Negative stains
Molecular / cytogenetics description
Molecular / cytogenetics images

Contributed by P.J. Cimino, M.D., Ph.D. and Chris Dampier, M.D.
SCNA plot

SCNA plot

Videos

Dysembryoplastic neuroepithelial tumor (DNET)

Sample pathology report
  • Brain, temporal lobe, biopsy:
    • Dysembryoplastic neuroepithelial tumor, CNS WHO grade 1
    • Positive for FGFR1 alteration
Differential diagnosis
Board review style question #1

The tumor shown above is from the mesial temporal lobe of a child. What is the most common underlying genetic alteration in this entity?

  1. BRAF V600E mutation
  2. FGFR1 alteration
  3. IDH1 R132H
  4. NF1 loss
  5. TP53 mutation
Board review style answer #1
B. FGFR1 alteration. TP53 mutations are uncommon in dysembryoplastic neuroepithelial tumor (E). IDH1 R132H is the most common mutation in IDH mutant astrocytomas and oligodendrogliomas but should be negative in dysembryoplastic neuroepithelial tumor (C). BRAF p.V600E mutation has been reported in dysembryoplastic neuroepithelial tumor but methylation profiling indicates such tumors are probably a distinct entity (A). NF1 loss may occur in dysembryoplastic neuroepithelial tumor but is rare (D).

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Reference: Dysembryoplastic neuroepithelial tumor
Board review style question #2
Which of the following is true of dysembryoplastic neuroepithelial tumors?

  1. Associated with NF2
  2. Associated with seizures
  3. Harbor several cytogenetic alterations
  4. Most frequently occur in adults
  5. Show diffuse CD34 immunoreactivity
Board review style answer #2
B. Associated with seizures. Dysembryoplastic neuroepithelial tumor should not show significant CD34 immunopositivity (E). Dysembryoplastic neuroepithelial tumor usually occurs in children (D). Dysembryoplastic neuroepithelial tumor is generally without chromosomal losses or gains, resulting in a flat copy number profile (C). Dysembryoplastic neuroepithelial tumor has rarely been associated with NF1 but not NF2 (A).

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Reference: Dysembryoplastic neuroepithelial tumor
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