CNS I Path - Neoplasia

Question 1

What is the most common type of brain tumor?

Answer 1

METASTASIS resulting from lung and breast

25-50% of tumors in the CNS; appear as clusters “snow storm” on imaging

Question 2

3 Distinct Syndromes of CNS Tumors

Answer 2

Increased ICP causes non-focal changes in the personality, gait and endocrine function of an affected patient’s brain

If the growth occurs in a high use area like Broca’s or the left occipital lobe there may be specific/focal deficits to help localize tumor

May present with partial or generalized SEIZURES

Question 3

Why are brain neoplasms so deadly?

Answer 3

HERNIATION!!!!! So benign and malignant classifications don’t mean shit cause this still could result in herniation

Question 4

Where does herniation occur?

Answer 4

“Choke-points” in the CNS –> Falx-Cerebri, Foramen Magnum, Calvarium (surgically created to relieve pressure), Uncal herniation against the BRAINSTEM (CN III deficits)

Question 5

Papilledema

Answer 5

Bulging of the optic disc into the vitreous humor of the eye –> another consequence of increased ICP

Question 6

What are the 3 types of glial cells and thus glial tumors?

Answer 6

ASTROCYTES –> Astrocytomas

OLIGODENDROCYTES –> Oligodendroglioma

EPENDYMAL –> Ependymomas

Question 7

4 stages of Astrocytomas?

Answer 7

Pilocytic (low grade), Diffuse Low Grade, Anaplastic, Glioblastoma Multiforme (high grade!)

Progression between these is common

Question 8

PILOCYTIC ASTROCYTOMAS

Answer 8

Lowest grade

Only one that is considered “non-invasive”

Composed of BIPOLAR CELLS with long “HAIR-LIKE” projections

CHILDREN!!!!!!!!!! Young adults

Cystic or solid growth in the CEREBELLUM with little invasion of the surrounding tissue –> early detection and surgical resection may be CURATIVE

Question 9

DIFFUSE LOW GRADE ASTROCYTOMA

Answer 9

Slowest growing, but INVASIVE still

Appears GRAY, POORLY DEFINED, can be tiny or span the whole hemisphere

Increased GLIAL CELLULARITY, mild pleomorphism, meshwork of thin astrocytic processes

May appear well demarcated, but INVASION BEYOND THE TUMOR MARGINS IS ALWAYS PRESENT (whether you see it or not)

5 year survival is good, because of slow growth

Question 10

ANAPLASTIC ASTROCYTOMA

Answer 10

Similar to the diffuse low grade – but with INCREASED CELLULARITY within the tumor, MORE PLEOMORPHISM, and SPORADIC MITOTIC SPINDLES

Hyperintense central masses surrounded by a HYPOintense border (edema)

Highly invasive although appears well-circumscribed

Likely extend far beyond the visual borders

Question 11

GLIOBLASTOMA MULTIFORME

Answer 11

Most aggressive of the astrocytomas

Can arise from the other glial tumors, or de novo

Nasty looking, lots of variation –> some areas FIRM, white; other areas YELLOW and gelatinous (liquefactive necrosis); could also be actively hemorrhaging!

Looks like anaplastic astrocytomas (high cellularity) but it also has REGIONS OF NECROSIS and VASCULAR/ENDOTHELIAL PROLIFERATION! —> alternating areas of dense cellularity and necrosis = PSEUDOPALLISADING

Question 12

Prognosis of GBM

Answer 12

Most COMMON primary brain tumor –> Tend to present de novo in OLDER patients; mortality is VERY HIGH!!!

25% live longer than 2 years DESPITE surgery, radiation and chemo :(

Mostly palliative care

Question 13

OLIGODENDROGLIOMAS overview

Answer 13

Also exist low grade (oligodendroglioma) and high grade (anaplastic oligodendroglioma or GBM)

Anaplastic have HIGHER CELLULARITY, SOME NECROSIS and MITOTIC CHANGES

All oligos have preference for WHITE MATTER, and are found PREDOMINANTLY in the cerebral hemispheres

Question 14

Oligodendromas Gross and Histo

Answer 14

Grossly –> well-circumscribed gray masses composed of CYSTS, CALCIFICATIONS, and FOCAL HEMORRHAGES (sometimes)

Microscopically FRIED EGG APPEARANCE!!!!

Survival is better than astrocytomas (5-10 year survival) –> almost ALL LOW GRADE PROGRESS TO HIGH GRADE

Random 1p and 19q chromosomal deletions have better response to treatment and thus better prognosis

Question 15

EPENDYMOMAS and PERIVENTRICULAR MASSES

Answer 15

Arise from ependymal cells of the cranial ventricles and spinal cord –> most often found intracranially in CHILDREN (4th ventricle) –> can thus cause HYDROCEPHALUS

Gross – solid or papillary looking masses arising from the floor of the ventricles

Histo –> DENSELY packed with intermittent CANALS (Rosettes); When they form around vessels –> Pseudorosettes!!!

Choroid Plexus Papilloma – tends to occur in children and messes with choroid function and structure –> hydrocephalus following blockade of a ventricular foramen

Question 16

MEDULLOBLASTOMA

Answer 16

Poorly differentiated PEDIATRIC TUMOR of the CEREBELLUM

Highly malignant/metastatic –> can seed throughout the CNS via the CSF

Typically well-circumscribed and highly anaplastic (lack of differentiation)

ROSETTES WITHOUT A CENTRAL CANAL (unlike the ependymomas)

Deadly if untreated, very sensitive to radiation!

Question 17

So what are 3 common CHILDHOOD CNS tumors?

Answer 17

Pilocytic astrocytomas (Low grade)

EPENDYMOMAS

MEDULLOBLASTOMAS (highly metastatic!!!)

Question 18

MENINGIOMAS overview

Answer 18

Most common form of EXTRA-AXIAL brain tumors (in the skull but outside the brain parenchyma)

I = Meningioma
II = Atypical Meningioma
III = Malignant Meningioma

All are relatively WELL-CIRCUMSCRIBED but HIGHER-GRADED masses grow FASTER and RECUR much more frequently

10% of Grade I recur, almost 100% of grade III recur

Most Grade I are benign, contained outside of brain tissue

All could cause problems like increased ICP and herniation!

2nd most common Primary CNS tumor

Question 19

Meningiomas Gross and Histo

Answer 19

Usually found attached to the dura, and arise from meningothelial cells of the arachnoid –> appear uniformly hyperintense with TAILS that push out into the meninges on each side of the tumor

Syncytial meningiomas form “WHORLED” structures

PSAMOMMATOUS MENINGIOMAS –> PSAMMOMA BODIES (laminated calcifications)

Question 20

CNS Metastasis

Answer 20

Most common cause of brain tumors!! Frequently LUNG AND BREAST origin

if a tumor in the CNS is found, MUST CT THE CHEST!!!!

Brain has NO LYMPHATICS so tumors reach the brain HEMATOGENOUSLY

Tend to have CRISP BORDERS with the normal CNS tissue –> CNS originating tumors have jagged/undefined borders!