Brain Tumor DSA 2 Flashcards
Meningioma
MC CNS tumor
meningioma
Most common symptoms of meningioma
seizures
focal neurologic deficits
(they do not herniate)
Patients with meningiomas of the spinal cord have an increased risk of developing _______.
bilateral schwannomas of the 8th cranial nerve
most common location for meningiomas
parasagittal area over cerebral convexities
meningothelial or syncytial meningioma
(epithelial appearance w/indistinct borders; pic for reference to other meningioma histology)
Transitional meningioma
(note: whorls of tumor cells some epithelial, some fibroblastic appearing)
_______% of meningiomas are anaplastic
1-3
______% of meningiomas are atypical
25
(low-grade; increased mitotic index, brain invasion, increased recurrence rate)
medulloblastoma
(always arise in the cerebellum)
medulloblastoma tumors arise from ______
primitive neuroectodermal cells derived from the external granular cell layer of the cerebellum
medulloblastomas are rapidly growing tumors that can lead to ______.
hydrocephalus by compressing the 4th ventricle (red arrow)
All medulloblastomas are WHO grade _______.
grade IV
Name 2 subcategories of medulloblastoma based on molecular subtypes
- Wnt activation of signaling pathway involved in normal cerebellar developmen
- Sonic hedgehog activation (SHH)
Dx? Why?
- classic medulloblastoma
- “small blue cells” (high N/C ratio)
(highly cellular sheet of primitive appearing cells)
Black arrows
Homer-wright rosettes
yellow arrow
homer-wright rosette: tumor cells surround an anuclear area of cytoplasmic processes from tumor cells
Dx? Why?
- medulloblastoma
- nests & cords of small round to elongated hyperchromatic tumor cells w/high N/C ratio
Medulloblastomas are undifferentiated tumors that lack _____ or _____ markers.
- neuronal
- glial
Medulloblastomas are _____ positive.
Ki-67: a marker of cellular proliferation
This is a _______ variant of a medulloblastoma.
desmoplastic/nodular
(numerous reticulin fibers; dark staining = Ki-67)
Tumor cells are arranged here in thin cords, where would you see this pattern form?
periphery of tumor; where it invades the subarachnoid space
(medulloblastoma)
Why do medulloblatoma patients receive radiation to the entire neuraxis?
it disseminates to the subarachnoid space and possibly down to the cauda equina (“drop metastases”)
(pic: periphery of tumor that invades the pia and disseminates)
Medulloblastoma survival rate? If it has metastasized?
- 70%
- 60%
Medulloblastoma WNT-subtype survival rate at 5 years
90%
Primary CNS lymphoma
Primary lymphoma tumors in the CNS are located in the ______.
deep within the cerebral hemispheres (near the lateral ventricles
(often bilateral)
Secondary CNS lymphomas are located ______
meninges or CSF
(rarely involve brain parenchyma)
MC CNS neoplasm is found in ______ patients
AIDS or immunocompromised
Dx? Why?
- primary CNS lymphoma
- round & dark blue cells
(no cohesion which is seen in carcinoma)
Primary CNS tumors are _______ (marker) positive.
CD20
(vast majority of primary CNS tumors are B-cell lymphomas)
Primary lymphoma patients who are immunosuppressed have markers for ______ infection. In non-immunosuppressed patients, they have _______ (mutation).
- EBV
- PDL1 amplification
(EBV → immunosuppression → lymphoma)
PDL1 gene function
encodes checkpoint proteins that inhibit T-cell responses
(PDL1 over-expression → decreases T cell response → B-cell lymphoma → primary CNS lymphoma)
The yellow arrows show tumor cells that are arranged _______.
around blood vessels
(primary CNS lymphoma)
________ (histologic characteristic) is highly indicative of primary CNS lymphoma
Angiocentric growth pattern (around blood vessels - yellow arrow)
Prognosis
poor - primary CNS lymphomas are aggressive tumors
Dx? Why?
- Germinoma: germ cell tumor
- Sheets of germ cells w/abundant clear cytoplasm
What must be excluded before a diagnosis of primary germ cell tumor?
non-CNS primary germ cell tumor (metastasis is common)
Dx? Why?
- Von Hippel-Lindau disease
- many small blood vessels w/RBCs, stromal cells w/pale pink cytoplasm & vacuoles.
This is due to a germline mutation in the _____ gene on chromosome ____.
- VHL
- 3p
Von Hippel-Lindau disease causes _______ (tumor)
hemangioblastoma
In addition to hemangioblastomas (pictured), Von Hippel-Lindau disease also causes _______(2 diz)
- renal cell carcinoma (clear cell type)
- pheochromocytoma
VHL gene function
encodes tumor suppressor protein pVHL
(MC result : hemangioblastoma - pictured)
What happens when pVHL activity is lost?
pVHL is a component of ubiquitin ligase lost → HIF1 (hypoxia induced factor) is overactive → VEGF & erythropoietin → excessive blood vessel growth
Stromal cells (pink cells w/abundant clear cytoplasm ww/vacuoles) are the neoplastic element of hemangioblastomas. They express _______ (3).
- erythropoetin
- VEGF
- inhibin
Neoplastic stromal cells seen Von Hippel-Lindau hemangiomas are derived from _______.
early mesenchymal progenitor cells
(capable of differentiating into endothelial and hemopoietic cells)
Hemangioblastomas are _______ (grade) and _______ (slow/fast) growing tumors.
- WHO grade I
- slow-growing
_______ are exquisitely radiosensitive brain tumors.
Medulloblastomas
Schwannomas are typically found in _______ (location)
Antoni A: cellular (yellow)
Antoni B: myxoid (red)
Dx? Why?
- Schwannoma
- Verocay bodies
Verocay bodies
tumor cells are palisading around anuclear consisting of cytoplasmic processes from tumor cells.
(Characteristic of schwannoma)
define schwannosis
schwann cells in the spinal cord
meningioangiomatosis
proliferation of meningeal cells and blood vessels that grow into the brain
Glial hamartia
microscopic nodular collections of glial cells at abnormal locations (i.e. superficial and deep layers of cerebral cortex)
neurofibroma: benign nerve sheath tumor
(more heterogeneous than schwannomas)
Neurofibromas composition (4)
- perineural-like cells
- fibroblasts
- mast cells
- CD34+
Neurofibromas are usually benign, but may become malignant in _______ (diz).
Neurofibromatosis type 1 (NF1)
Neurofibromas arise from ______ (2).
- peripheral nerves (including spinal nerve roots)
- skin
3 growth patterns of neurofibromas
- superficial cutaneous
- diffuse
- plexiform
What is the main distinction between neurofibromas and schwannomas?
neurofibromas are dispersed throughout the nerve axons
(schwannomas do not)
Why are schwannomas easier to excise than neurofibromas, sparing nerve function?
they do not course through the nerve and axons
What are the main histologic differences between neurofibromas and schwannomas?
neurofibromas: wavy, spindle shaped cells embedded in collagenous stroma & are more homogenous
Neurofibromatosis Type 1 affects one in ______ people
3,000
In addition to neurofibromas, patients with NF1 may also develop _______ (2)
- optic nerve tumors
- pheochromocytomas
NF1 patients have ______ (3 symptoms).
- seizures
- nodules of iris (Lisch nodules)
- cafe au lait spots
NF1 gene function
encodes tumor suppressor protein neurofibromin
Neurofibromin is a GTPase activating protein (GAP) that binds ______→______.
RAS proteins → returning alpha subunit to inactive state›
plexiform neurofibroma
What makes a plexiform neurofibroma unique?
involves the individual fascicles of a nerve and extend along the course of the nerve
Plexiform neurofibromas may be single lesions or multiple. Single lesions are associated with ______.
neurofibromatosis type 1
Plexiform neurofibroma
(note individual nerve fascicles are expanded by tumor having a myxoid stroma)
In plexiform neurofibromas, there is a homozygous alteration of ______ in the schwann cell component.
NF1 gene
Dx? Why?
- Malignant peripheral nerve sheath tumor (MPNSTs)
- Spindle-shaped cells
Malignant Peripheral Nerve Sheath tumors are typically malignant forms of _______.
plexiform neurofibromas
(usually start in large peripheral nerves of chest, abdomen, pelvis, neck or limb girdle)
_______% of malignant peripheral nerve sheath tumors arise in patients with NF1.
50
triton tumor
malignant peripheral nerve sheath tumor that exhibits rhabdomyoblastic differentiation
