CNS Neoplasm Flashcards
Pilocytic Astrocytoma - Characteristics
Most common CNS neoplasm of childhood
Well circumscribed, non-infiltrative WHO Grade I tumor; often found in the cerebellar hemispheres, optic nerve, and hypothalamus; usually doesn’t undergo malignant transformation and can be treated by surgical resection
Pilocytic Astrocytoma - Histopathology
Neoplastic cells with elongated, hairlike processes arranged in parallel bundles; associated with Rosenthal fibers and some cystic areas containing mucin
Pilocytic Astrocytoma - Genetics
May show a BRAF:KIAA fusion; BRAF is a protein kinase that plays a key role in cell survival/differentiation/apoptosis pathways
Never possesses IDH1/2 mutation
Diffuse Astrocytoma - Characteristics
WHO Grade II tumor with median age of onset 30-40s; usually affects cerebral hemispheres diffusely but does not metastasize outside of CNS
NOT surgically resectable; treated with radiation
Diffuse Astrocytoma - Histopathology
Diffusely infiltrative with ill-defined borders; no microvascular proliferation or necrosis
Anaplastic Astrocytoma - Characteristics
WHO Grade III Tumor with mean age of onset 45 years; usually affects cerebral hemispheres
Anaplastic Astrocytoma - Histopathology
Higher cellularity, increased nuclear pleomorphism, and mitoses compared to WHO Grade II Diffuse Astrocytoma; no necrosis or microvascular proliferation
Diffuse Astrocytoma - Genetics
IDH Mutation + TP53 mutation/17P loss
Oligodendroglioma - Characteristics
5-15% of all gliomas; can be WHO Grade II or III with mean age of onset ~40 years
Usually arises in cerebral white matter
Often presents as seizures
Not curable by resection - better prognosis than diffuse astrocytoma
Oligodendroglioma - Histopathology
Low to moderate cellularity with occasional mitoses; cells have round, monotonous nuclei containing little or no cytoplasm with a “fried egg” appearance
Anaplastic Astrocytoma - Genetics
IDH mutation + TP53 mutation/17p loss + 9p loss
Genetic progression of diffuse astrocytoma
Anaplastic oligodendroglioma - histopathology
Same as oligodendroglioma WHO Grade II (round, monotonous nuclei with scant cytoplasm and “fried egg” appearance) with increased cellularity, nuclear atypia, mitoses, with occasional vascular proliferation OR necrosis
Oligodendroglioma - Genetics
IDH Mutation + 1p/19q co-deletion
Anaplastic oligodendroglioma - Genetics
IDH Mutation + 1p/19q co-deletion + 9p/10q loss
Genetic progression of WHO Grade II oligodendroglioma
Glioblastoma - Characteristics
WHO Grade IV, accounting for 15% of all intracranial neoplasms; 90% arise sporadically (primary GBM) and 10% occur as a result of progression from lower grade astrocytomas (secondary GBM)
Glioblastoma - Histopathology
4 diagnostic criteria:
- Nuclear abnormalities (atypia, hyperchromatism, variation in size/shape)
- Mitotic activity
- Microvascular proliferation
- Necrosis
Primary vs. Secondary GBM
Age of onset - Older for primary GBM (55 years) vs. secondary GBM (45 years)
Duration of symptoms - shorter for primary GBM (<3 months) vs. secondary GBM
Ependymoma - Characteristics
Most present in the first 2 decades of life in the 4th ventricle, causing obstructive hydrocephalus; in adults, more likely to occur in the spinal cord
Ependymoma - Histopathology
Formation of perivascular pseudorosettes, a perpendicular arrangement of cells around blood vessels with the formation of elongated cell processes
Choroid Plexus Papilloma - Characteristics
Neoplastic proliferation of choroid papillary formations occurring more frequently in the lateral ventricles in adults and in the IVth ventricle in children, often producing obstructive hydrocephalus
WHO Grade I, usually curable by surgical resection
Medulloblastoma - Characteristics
Most common malignant brain tumor in children; peak incidence 3-8 years
WHO Grade IV with a tendency to spread throughout the CSF
Medulloblastoma - Histopathology
Arises from the granule progenitor cells of the external granule layer; proliferation of patternless sheets of embryonal cells with scant cytoplasm, presence of Homer Wright rosettes (circular rings of nuclei with a central, anuclear area filled with cell processes)
Medulloblastoma - clinical presentation
Increased ICP signs due to obstructive hydrocephalus of the IVth ventricle: headache, vomiting, papilledema, gait disturbances, nystagmus
Meningioma - Characteristics
Most common intracranial neoplasm, peak incidence is women in their 50-60s; usually WHO Grade I but can progress to more advanced grades through accumulation of mutations
Usually solitary; complications include: penetration of the dura, occlusion of venous sinuses, invasion of bone, hyperostosis
Schwannoma - Characteristics
Slow growing tumors found on cranial nerves 3-12 and spinal nerve roots; malignant transformation is rare
Acoustic Neuroma
i.e. Vestibular (CN VIII) Schwannoma
Bilateral vestibular schwannoma is characteristic of Neurofibromatosis Type II
Familial Tumor Syndromes
Neurofibromatosis - Types I and II Tuberous Sclerosis Von Hippel Lindau Disease Cowden Disease Turcot's Syndrome
Which systemic tumors most commonly metastasize to the brain?
Breast Lung Kidney Melanoma GI tract
*Solid neoplasms of childhood rarely metastasize to the brain
