Brain Tumour MCQs (Part 2)

Pilocytic Astrocytomas

• a subgroup of astrocytomas (WHO grade I) with better prognosis (10-year survival: > 95%) than
• infiltrating fibrillary or diffuse astrocytomas
• the most common astrocytic tumor in children
• average age is lower than for typical astrocytomas (75% of patients are ≤ 20 yrs)
• Common locations: cerebellar hemisphere, optic nerve/chiasm, hypothalamus
• CT/MRI appearance: discrete appearing, contrast enhancing lesion.
• Cerebellar PCAs are classically cystic with mural nodule
• the principal CNS tumor associated with NF1
• pathology: biphasic. 1) Compacted, 2) loose textured astrocytes with Rosenthal fibers and/or eosinophilic granular bodies
• danger of overgrading and overtreating if not recognized. Histology alone may be inadequate for
• diagnosis; knowledge of patient age & radiographic appearance is critical

complete surgical resection, when possible, is usually curative. For cystic PCAs with enhancing mural nodule, only the nodule needs to be resected (the cyst wall is not neoplastic). XRT is used post-op only for nonresectable recurrence or malignant degeneration

Explanation:

Central neurocytoma (WHO grade II)

• rare, WHO Grade II neuronal tumor
• primarily seen in young adults. Typically intraventricular, attached to septum pellucidum
• gross total resection can be curative (but some recur even after GTR)
• if MIB-1 labeling index > 2–4%, there is an increased risk of recurrence after subtotal resection
• if MIB-1 labeling is elevated, radiation therapy after subtotal resection can reduce the risk of recurrence

Ref: Greenberg Textbook of Neurosurgery, 9th Edition, Chapter 38

Explanation:

Oligodendroglioma

• slow growing tumor that frequently presents with seizures
• occur primarily in adults, predilection for the frontal lobes
• by definition: a diffusely infiltrating glioma with codeletion of BOTH chromosome arms 1p AND
• 19q, AND mutation of IDH1 OR IDH2
• histology: classic features of “fried egg” cytoplasm (on permanent pathology) & “chicken wire” vasculature are unreliable. Calcifications are common
• recommended treatment: as for WHO grade II astrocytic tumors

Ref: Greenberg Textbook of Neurosurgery, 9th Edition, Chapter 36

Explanation:

Brainstem Gliomas

• not a homogeneous group. MRI can differentiate malignant from benign lesions
• trend: lower grade tumors tend to occur in the upper brainstem, and higher grade tumors in the lower brainstem/medulla
• usually presents with multiple cranial nerve palsies and long tract findings
• most are malignant, have poor prognosis, and are not surgical candidates
• role of surgery primarily limited to dorsally exophytic lesions and shunting

Ref: Greenberg Textbook of Neurosurgery, 9th Edition, Chapter 37

Explanation:

The pituitary gland, situated within the sella turcica derives its name from the Greek ptuo and Latin word pītuītārius pertaining to or secreting phlegm.

Galen hypothesized that nasal phlegm originated from the brain and drained via the pituitary gland

Ref: https://en.wikipedia.org/wiki/Pituitary_gland

Explanation:

Ependymal Tumors

• slow growing, WHO grade I
• arise from ependymal lining of, and protrude into, the ventricle
• almost always an incidental finding; hydrocephalus when symptomatic
• treatment: Gross total removal, when possible, is the goal if intervention is indicated

Ref: Greenberg Textbook of Neurosurgery, 9th Edition, Chapter 38

Explanation:

Oligodendroglioma

• slow growing tumor that frequently presents with seizures
• occur primarily in adults, predilection for the frontal lobes
• by definition: a diffusely infiltrating glioma with codeletion of BOTH chromosome arms 1p AND
• 19q, AND mutation of IDH1 OR IDH2
• histology: classic features of “fried egg” cytoplasm (on permanent pathology) & “chicken wire” vasculature are unreliable. Calcifications are common
• recommended treatment: as for WHO grade II astrocytic tumors

Ref: Greenberg Textbook of Neurosurgery, 9th Edition, Chapter 36

Explanation:

Ependymoma. RELA fusion-positive (WHO grade II or III)

• A supratentorial ependymoma characterized by presence of an RELA fusion gene.
• Comprise ≈ 70% of supratentorial childhood ependymomas, and almost none of the infratentorial tumors
• Grading: These tumors are graded based on histology as either grade II or III (no grade I ependymomas have been found with this gene).
• Based on the only study available at the time of the classification, this group has the worst prognosis of the 3 supratentorial varieties

Ref: Greenberg Textbook of Neurosurgery, 9th Edition, Chapter 38

Explanation:

Intracranial Ependymomas

• usually benign tumors, often fibrillary with epithelial appearance.
• Perivascular pseudorosettes or true rosettes may be seen in classic (papillary) form
• most often occur in the floor of the 4th ventricle, presenting with hydrocephalus (increased ICP) and cranial nerve VI & VII palsies
• evaluation: includes imaging the entire neuraxis (usually with enhanced MRI: cervical, thoracic, lumbar & brain) because of potential for seeding through CSF
• worse prognosis the younger the patient (especially age < 24 months)
• treatment: the best outcomes are associated with gross total removal (no enhancing tumor on post-op MRI) followed by XRT. XRT may be withheld for age < 3
• do LP ≈ 2 weeks post-op to send ≈ 10 cc of CSF for cytology for prognostication

Ref: Greenberg Textbook of Neurosurgery, 9th Edition, Chapter 38

It consists of a classical triad of

• Ipsilateral anosmia
• Ipsilateral optic atrophy
• Contralateral papilledema

Named after neurologist Robert Foster Kennedy.

Usually from olfactory groove or medial third sphenoid wing tumor (usually meningioma).

Now rare due to early detection by CT or MRI. Classic triad:

Occasionally ipsilateral proptosis will also occur due to orbital invasion by tumor.