Neuronal/Glioneuronal Tumors

Question 1

Dysembryoplastic Neuroepithelial Tumor (DNET):
-Mutation
-Age
-Location
-Grade

Answer 1

-FGFR1 activating mutations
-Infant to Young Adults
-Temporal lobe (~67%) and Frontal lobe (~16%)
-WHO grade 1

Question 2

Ganglioglioma:
-Location
-Imaging

Answer 2

-Temporal lobe (~77%)
-Circumscribed, Solid & Cystic w/ enhancing mural nodule

Question 3

Ganglioglioma:
-Mutation
-Age
-Grade

Answer 3

-BRAF p.V600E (10-60%) or other MAPK pathway alterations
-Median: 12 y/o (can be seen in all ages)
-WHO grade 1

Question 4

Gangliocytoma:
-Age
-Location
-Grade

Answer 4

-Children w/ epilepsy
-Temporal lobe (~80%)
-WHO grade 1

Question 5

Dysplastic Cerebellar Gangliocytoma (Lhermitte-Duclos Disease):
-Associated Syndrome
-Mutation

Answer 5

-Cowden’ts syndrome (PTEN hamartoma syndrome) - 32%
-PTEN mutation/deletion or loss of expression

Question 6

Dysplastic Cerebellar Gangliocytoma (Lhermitte-Duclos Disease):
-Histology

Answer 6

-Densely packed ganglionic cells of various size
-Abnormal myelination and vacuolization in the outer molecular layer
-Calcification and ectatic vessels

Question 7

Papillary Glioneuronal Tumor:
-Mutation

Answer 7

PRKCA gene fusion (SLC44A1::PRKCA fusion - primarily)

Question 8

Papillary Glioneuronal Tumor:
-Location
-Age
-Grade

Answer 8

-Suptratentorial (temporal lobe MC; ~28%)
*close to the lateral ventricles
-Young Adults (median: 16 y/o)
-WHO grade 1

Question 9

Desmoplastic Infantile Astrocytoma (DIA)/Gangliogloma (DIG):
-Histology

Answer 9

-Prominent desmoplastic stroma (involving leptomeninges) mixed with benign astrocytic with or without neuronal component
*Reticulin-rich basal lamina surrounding every cell (mimics mesenchymal tumor)
*Foci of undifferentiated embryonal-like tumor cells also present

Question 10

Desmoplastic Infantile Astrocytoma (DIA)/Gangliogloma (DIG):

Question 10

Desmoplastic Infantile Astrocytoma (DIA)/Gangliogloma (DIG):
-Mutation
-Location
-Imaging
-Age
-Grade

Answer 10

-BRAF or RAF1 mutation or fusion (MAPK pathway)
-Supratentorial involving leptomeninges and dura
-Large, solid and cystic; contrast enhancing (solid portion often involves dura)
-Infants (before 24 months)
-WHO grade 1

Question 11

Rosette-Forming Glioneuronal Tumor:
-Mutation
-Associated syndromes

Answer 11

-FGFR1 mutation w/ frequent co-occurrence of a PIK3CA and/or NF1 mutation
-Noonan Syndrome or NF1

Question 12

Rosette-Forming Glioneuronal Tumor:
-Location
-Age
-Grade

Answer 12

-Midline; Fourth Ventricle and/or Aqueduct
-Children to Young Adults; RARE
-WHO grade 1

Question 13

Rosette-Forming Glioneuronal Tumor:
-Histology (2 distinct components)

Answer 13

-Uniform neurocytes forming rosettes and/or perivascular pseudorosettes
*Synaptophysin positivity
-Astrocytic component resembling pilocytic astrocytoma

Question 14

Diffuse Leptomeningeal Glioneuronal Tumor:
-Histology
-Mutation

Answer 14

-Oligodendroglioma-like cells and pilocytic astrocytoma features with diffuse leptomeningeal involvement
-Chromosome arm 1p deletion and
-MAPK gene alteration - KIAA1549::BRAF fusion (Most Common)
*IDH-Wildtype

Question 15

Diffuse Leptomeningeal Glioneuronal Tumor:
-Location
-Age

Answer 15

-Spinal and intracranial leptomeninges
-Median: 5 y/o (range 5 months - 40 years); RARE

Question 16

Central Neurocytoma:
-Location
-Age
-Histology
-Grade

Answer 16

-Intraventricular (Lateral or Third ventricle)
-Mean: 28.5 y/o (70% between 20-40)
-Uniform round cells (oligo-like) with speckled chromatin (Synaptophysin +); Calcifications in 50%
-WHO grade 2

Question 17

Extraventricular Neurocytoma:
-Mutation

Answer 17

FGFR1::TACC1 fusions (MC)
*IDH-Wildtype

Question 18

Extraventricular Neurocytoma:
-Location
-Age
-Grade

Answer 18

-Cerebral hemispheres and Cerebellum (W/O ventricle involvement)
-Adults (20-40 y/0)
-WHO grade II

Question 19

Cerebellar Liponeurocytoma:
-Age
-Grade

Answer 19

-Adults (mean: 50 y/o)
-WHO grade 2