Robbins Flashcards
most common group of primary brain tumors
Gliomas
two major categories of astrocytic tumors
diffusely infiltrating astrocytomas (WHO grade II to IV) and the more localized astrocytomas (ie. pilocytic astrocytoma, WHO grade I)
Secondary glioblastomas and their lower-grade precursors are associated with driver mutations of (2)
IDH1 and IDH2
T/F most primary glioblastomas are IDH–mutant, WHO grade IV
False, most primary glioblastomas are IDH–wild type, WHO grade IV
Diffuse Astrocytoma vs Anaplastic
more densely cellular, more notable nuclear atypia and presence of mitosis
Anaplastic astrocytoma vs Glioblastoma
features of anaplastic + necrosis and hypervascularity
Mutations in primary glioblastoma (4)
TERT, EGFR, CDKN2A, TP53
Primary vs secondary glioblastoma
Primary - older, no precursor lesion, IDH-wild type, TERT mutations
Secondary - younger, with precursor astrocytoma, IDH mutant, ATRX mutant
Oligodendroglioma is molecularly defined by IDH ____ and codeletion of
mutant, and codeletion of 1p and 19q
brain tumor composed of sheets of regular cells with spherical nuclei containing finely granular chromatin surrounded by a clear halo of vacuolated cytoplasm and typically contains a delicate network of anastomosing capillaries, resembling “chicken wire.”
Oligodendroglioma
distinct genetic alteration in Pilocytic astrocytoma (WHO grade 1)
KIAA1549-BRAF gene fusion/ duplication
brain tumor with a biphasic architecture combining loose “microcystic” and compact, densely fibrillar areas.
Pilocytic astrocytoma
T/F presence of microvascular proliferation or necrosis in Pilocytic astrocytoma implies an unfavorable prognosis
False
Characteristic finding in Pilocytic astrocytoma (4)
biphasic, limited brain invasion, hair-like processes, rosenthal fibers
tumors that most often arise in proximity to the ependyma-lined ventricular system, including the oft-obliterated central canal of the spinal cord.
Ependymoma
commonly mutated in ependymomas arising in the spinal cord
NF2 gene
distinct lesions that occur in the filum terminale of the spinal cord. Cuboidal tumor cells are arranged in a variably papillary architecture around mucin-rich fibrovascular cores.
Myxopapillary ependymomas (WHO grade I)
tumors composed of a mixture of mature neuronal and glial cells. They are typically superficial lesions that present with seizures and are the most common neuronal tumors in the CNS
Gangliogliomas (WHO grade I)
Approximately 20% to 50% of gangliogliomas have an activating mutation in
BRAF V600E
most common brain embryonal neoplasm which occurs predominantly in children and exclusively in the cerebellum
medulloblastoma
Molecular subtypes of medulloblastoma reveal alterations of signaling pathways (2)
sonic hedgehog–patched (SHH) pathway and WNT/β-catenin signaling pathway
characteristic finding in classic subtype of medulloblastoma
Homer Wright rosettes
most common CNS neoplasm in immunosuppressed individuals, including those with AIDS and immunosuppression after transplantation
Primary CNS lymphoma
Primary CNS lymphoma in the setting of immunosuppression, the malignant B cells are usually latently infected by
EBV
In those who are not immunosuppressed, primary CNS large B-cell lymphomas often have amplification and overexpression of what gene?
PDL1
Of sporadic meningiomas, 50% to 60% harbor mutations in what gene?
NF2
Mutations in TSC1 or TSC2 lead to increased and unregulated
mTOR activity
T/F Genetic changes that indicate an IDH-wild type astrocytoma will behave aggressively and should be graded as Glioblastoma, grade IV even if traditional morphologic findings of glioblastoma aren’t present
True
characteristic finding in ependymoma
pseudorosettes
meningioma subtypes that are considered grade 2
choroid and clear cell
meningioma subtypes that are considered grade 3
papillary and rhabdoid
herniation type that occurs when unilateral or asymmetric expansion of a cerebral hemisphere displaces the cingulate gyrus under the falx.This may lead to compression of the anterior cerebral artery and its branches, resulting in secondary infarcts.
Subfalcine (cingulate) herniation
herniation type that occurs when the medial aspect of the temporal lobe is compressed against the free margin of the tentorium, third cranial nerve is compromised, resulting in pupillary dilation and impaired ocular movements on the side of the lesion.
Transtentorial(uncal,mesialtemporal) herniation
Progression of transtentorial herniation is often accompanied by secondary hemorrhagic lesions in the midbrain and pons, termed
Duret hemorrhages
herniation type that refers to displacement of the cerebellar
tonsils through the foramen magnum.This pattern of herniation is life-threatening because it causes brainstem compression and compromises vital respiratory and cardiac centers in the medulla.
Tonsillar herniation
the most common neural tube defect and may be an asymptomatic bony defect or a severe malformation with a flattened, disorganized segment of spinal cord, associated with an overlying meningeal outpouching.
spina bifida
refers to an extrusion of malformed brain tissue through a midline defect in the cranium
Encephalocele
refers to extension of CNS tissue through a defect in the vertebral column
Myelomeningocele
is a malformation of the anterior end of the neural tube that leads to absence of most of the brain and calvarium
Anencephaly
posterior fossa anomaly which consists of a small posterior fossa, a misshapen midline cerebellum with downward extension of vermis through the foramen magnum
Arnold-Chiari malformation (Chiari type II malformation)
posterior fossa anomaly which consists of low-lying cerebellar tonsils extend down into the vertebral canal.
Chiari type I malformation
posterior fossa anomaly which is characterized by an enlarged posterior fossa. The cerebellar vermis is absent or present only in rudimentary form in its anterior portion; in its place is a large midline cyst that is lined by ependyma and is contiguous with leptomeninges on its outer surface.
Dandy-Walker malformation
depressed, retracted, yellowish brown patches involving the crests of gyri, most commonly those that are located at the sites of contrecoup injuries (inferior frontal cortex, temporal and occipital poles); these lesions are called
plaque jaune
the pathognomonic microscopic finding in rabies called _____, are cytoplasmic, round to oval, eosinophilic inclusions found in pyramidal neurons of the hippocampus and Purkinje cells of the cerebellum
negri bodies
