79. Brain Tumor Pathology

Question 1

Gliomas

-list the non-infiltrating and infiltrating types with grades

Answer 1

Non-infiltrating:

• Pilocytic Astrycytoma (GI)
• Ependymomas: GI, Anaplastic GIII, Myxopapillary GI

Infiltrating:

• Astrocytoma: Diffuse GII, Anaplastic GIII, GBM GIV
• Oligodendroglioma: GII, Anaplastic GIII

Question 2

Infiltrating Astrocytomas

• age/location
• gross
• histo for each grade
• genetics

Answer 2

-any age (40s-60s); cerebral hemispheres
-Gross: poorly defined, grey infiltrating mass
GII: diffuse - nuclear atypia (dark irregular nuclei of astrocytes)
GIII: anaplastic - nuclear atypia, increased mitoses
GIV: GBM - nuclear atypia, increased mitoses, endothelial proliferation, pseudopalisading necrosis (cross midline = butterfly pattern)

Genetics: GII/III - IDH mutations (accumulate more and become GIV)
GIV - primary - different genes than GII/III that progress to GIV

Question 3

Oligodendrogliomas

• age, location
• gross
• histo for each grade
• genetics

Answer 3

Age: 40s-50s
Location: cerebral hemispheres (white matter)
Gross: well-defined, soft, gray-pink mass
Histo: GII - round uniform nuclei w/ perinuclear halo (fried egg), chicken wire vasculature, microcalcifications
GIII - nuclear atypia (missing perinuclear halo, more mitoses, endothelial proliferation)

Genetics: IDH mutation, Loss of Ch1p19q (NEEDED FOR DX), higher grades have additional mutations

Question 4

Pilocytic Astrocytoma

• age, location
• assoc
• imaging
• gross
• histo

Answer 4

Age: young children, young adults
Location: cerebellum/lower brain
Assoc: NF1
Imaging: cyst w/ enhancing mural nodule
Gross: cyst w/ enhancing mural nodule
Histo: biphasic - compact fine piloid processes and loos microcystic areas; Rosenthal Fibers (pink red), few mitoses

Question 5

Ependymomas

• types
• location for each type
• assoc
• gross
• histo for each type

Answer 5

Gross: solid masses in ventricular space, well-demarcated

GI: myxopapilloma

• located in conus medullaris/cauda equina
• hist: round/oval uniform nuclei, papillary structures around central fibrovascular core with bluish/myxoid background
• assoc with NF2

GII: Ependymoma
- sheets of cells with round/oval nuclei; perivascular pseudorosettes, true ependymal rosettes (true lumen)

GIII: Anaplastic Ependymoma
- hypercellularity, more mitoses, endothelial proliferation, pseudopalisading necrosis

Question 6

Ganglioglioma

• grade
• location
• CP
• histo

Answer 6

GI - most common glioneuronal tumor
site: temporal lobe
CP: seizures
Histo: Rosenthal Fibers (like pilocytic astrocytoma), with multinucleated dysmorphic neurons

Question 7

Medulloblastoma

• grade
• age
• location
• gross
• histo

Answer 7

GIV - malignant
affects young children
site: post. fossa/cerebellum
Gross: large friable tumor in cerebellum
Histo: sheets of cells w/ dark nuclei, more mitosis, Homer-Wright Rosettes (around fibrillary material)

Question 8

Atypical Teratoid/Rhabdoid Tumor (ATRT)

• age/grade
• genetics

Answer 8

Pediatrics/Infants (<5yo)
GIV
Cells look like rhabdomyosarcoma = may express multiple lineage markers (epithelial, mesenchymal, neuroepithelial)

Genetics: loss/mutation of hSN5/INI1 gene on Ch22

Question 9

Meningioma

• location
• age/gender
• gross
• histo

Answer 9

Location: dural base/intraventricular
Age/Gender: adults, W>M 3:2
Gross: firm, round mass with well-defined dural base
Histo: syncytial appearance (loss of cell borders), WHORLED growth patten, Psammoma bodies (calcifications), Intranuclear pseudoinclusions