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Brain Tumors and Treatment Complications


INTRODUCTION

Background

  • Central nervous system (CNS) tumors are the second most common pediatric cancer diagnosed each year, accounting for approximately 25% of childhood cancers. They are responsible for the second most common cause of cancer deaths in children.

  • Survival has slowly improved over the years, and overall survival is now approximately 75%.

  • Supratentorial tumors predominate during the first 2 years of life and late adolescence, while infratentorial tumors are more common in the remainder of the first decade.

  • Presenting signs and symptoms are wide ranging, but common features include headache (especially morning headache), vomiting, lethargy, papilledema, seizure, and neurologic deficit. Some signs and symptoms are more specific to a location of tumor and are emphasized in this chapter.

  • Treatment varies, depending on the tumor pathology and location, and is briefly discussed in each section.

Imaging

  • Imaging is performed for obtaining a diagnosis or differential diagnosis, determination of tumor extent, and effect on the normal brain. Follow-up imaging is used to assess for recurrence/progression and complications of treatment.

  • A general approach for a new pediatric brain tumor for determining the diagnosis or narrow differential diagnosis includes the following:

    • Location and extent of the tumor: This chapter emphasizes a location-based approach

    • Conventional MRI appearance with emphasis on DWI appearance

    • Advanced imaging: MR Spectroscopy (MRS), Arterial Spin Label (ASL) perfusion, Dynamic Contrast Enhanced (DCE) perfusion, and Dynamic Susceptibility Contrast (DSC) perfusion

    • Determination of leptomeningeal disease in the remainder of the brain and spine

  • DWI is helpful for determining low grade (WHO grade 1–2) from high grade (WHO grade 3–4). High-grade tumors typically demonstrate DWI hyperintense and ADC hypointense signal relative to normal parenchyma, which is considered a reflection of tumor cellularity (low ADC = high cellularity).

  • MR perfusion imaging is helpful for tumors in which the conventional imaging patterns remain inconclusive. Generally, high cerebral blood flow (CBF) and cerebral blood volume (CBV) occur in high-grade tumors and are reflective of tumor microvascular density. An ASL CBF > 50 mL/min/100 g was shown to have sensitivity/specificity for differentiation of low-grade and high-grade pediatric brain tumors at the following locations: cerebral hemisphere (90%/93%), thalamic tumors (100%/80%), and posterior fossa tumors (65%/94%). Determination of specific histopathology remains challenging.

  • MRS can be useful when the convention pattern is indeterminate. However, the authors believe the conventional imaging patterns combined with MR perfusion have rendered MRS less favorable in the initial imaging of pediatric brain tumors. Utility may remain in situations of determining radiation necrosis from recurrent tumor.

REFERENCES

  • 1. Rumboldt Z., et. al.: Apparent diffusion coefficients for a differentiation of cerebellar tumors in children. AJNR Am J Neuroradiol Jun–Jul 2006; 27: pp. 1362-1369.
  • 2. Kralik S.F., et. al.: Diffusion imaging for tumor grading of supratentorial tumors in the first year of life. AJNR Am J Neuroradiol 2014 Apr; 35: pp. 815-823.
  • 3. Dangolouff-Ros V., et. al.: Arterial spin labeling to predict pediatric brain tumor grading in children: Correlations between histopathologic vascular density and perfusion MR imaging. Radiology 2016 Nov; 281: pp. 553-566.

POSTERIOR FOSSA TUMORS

MEDULLOBLASTOMA

Key Points

Background

  • WHO grade 4

  • Account for 30% to 40% of pediatric posterior fossa tumors

  • Five histologic subtypes:

    • Classic: Most common (>70%)

    • Desmoplastic/nodular

    • Large cell

    • Anaplastic

    • Medulloblastoma with extensive nodularity

  • Molecular subgroups better correlate with demographics, clinical features, and prognostication and may aid development of future molecular targeted therapies

    • Four molecular subgroups—prevalence:

      • Wingless (Wnt): 10%

      • Sonic Hedgehog (SHH): 30%

      • Group 3: 25%

      • Group 4: 35%

  • Gorlin syndrome (basal cell nevus syndrome) is associated with increased risk of medulloblastoma and discussed in Chapter 9 .

Imaging

CT

  • Midline (most common) or cerebellar hemispheric hyperdense tumor; commonly cysts or necrotic regions (50% to 90%); calcifications (10% to 40%); significant hemorrhage is uncommon

MRI

  • Most commonly arising from the inferior vermis, although location may be variable depending on molecular subtype

  • Well-circumscribed; T1W hypointense; T2W isointense to hypointense

  • Variable enhancement with majority demonstrating enhancement. Minority may show no enhancement

  • Restricted diffusion with ADC values <0.9 × 10 3 mm 2 /s

    • Metastatic disease at initial diagnosis in 11% to 43%

      • Posterior fossa, intraventricular, subfrontal, and spinal are most common locations for metastases

Advanced Imaging

  • MR Perfusion: ↑ CBF and CBV

  • MRS: ↑ Elevated taurine , choline, and lactate; ↓ NAA and creatine

REFERENCES

  • 1. Partap S., et. al.: Medulloblastoma incidence has not changed over time: a CBTRUS study. J Pediatr Hematol Oncol 2009; 31: pp. 970-971.
  • 2. Kijima N., et. al.: Molecular Classification of Medulloblastoma. Neurol Med Chir (Tokyo) 2016 Nov; 56: pp. 687-697.
  • 3. Dangouloff-Ros V., et. al.: Imaging features of medulloblastoma: Conventional imaging, diffusion-weighted imaging, perfusion-weighted imaging, and spectroscopy: From general features to subtypes and characteristics. Neurochirurgie 2018 Aug 28; S0028-3770(17)30178-9
  • 4. Rumboldt Z., et. al.: Apparent Diffusion Coefficients for Differentiation of Cerebellar Tumors in Children AJNR. Am J Neuroradiol 2006 Jun-Jul; 27: pp. 1362-1369.

MEDULLOBLASTOMA: MOLECULAR SUBTYPES

Graphical Summary of the 12 Medulloblastoma Subtypes.

Schematic representation of key clinical data, copy-number events, and relationship between the subtypes inside each of the four medulloblastoma subgroups. The percentages of patients presenting with metastases and the 5-year survival percentages are presented. The age groups are: infant 0–3 years, child >3–10 years, adolescent >10–17 years, and adult >17 years. (From Cavalli F, Remke M, Rampasek L, et al. Intertumoral heterogeneity within medulloblastoma subgroups. Cancer Cell . 2017;31:737–754.e6. https://doi.org/10.1016/j.ccell.2017.05.005)

Wnt Sonic Hedgehog Group 3 Group 4

MEDULLOBLASTOMA: WNT (WINGLESS)

Key Points

Background

  • Prevalence: 10% (rarest subgroup)

  • Histology: Classic

  • Prognosis: 5-year survival 95% (best prognosis)

  • Demographics: Older children and teens ; M:F ratio 1:1

Imaging

  • Location: Lateral location (foramen of Luschka, cerebellopontine angle [CPA]) ; is most common fourth ventricle, or cisterna magna are less common

  • Rarely presents with metastasis

REFERENCES

  • 1. Kijima N., et. al.: Molecular Classification of. Medulloblastoma. Neurol Med Chir (Tokyo) 2016 Nov; 56: pp. 687-697.
  • 2. Patay Z., et. al.: Magnetic resonance imaging characteristics of WNT-subgroup pediatric medulloblastoma. AJNR Am J Neuroradiol 2015 Dec; 36: pp. 2386-2393.
  • 3. Perreault S., et. al.: MRI surrogates for molecular subgroups of medulloblastoma. AJNR Am J Neuroradiol 2014 Jul; 35: pp. 1263-1269.

MEDULLOBLASTOMA: SONIC HEDGEHOG (SHH)

Key Points

Background

  • Prevalence: 30%

  • Histology: Desmoplastic/nodular and classic are most common; large cell/anaplastic possible

  • Prognosis: 5-year survival 75% (intermediate prognosis)

  • Demographics: Infants and teenagers/adults; M:F ratio 1:1

Imaging

  • Location: Vermis (infants), or cerebellar hemisphere (teenagers/adults)

  • Rarely presents with metastasis

REFERENCES

  • 1. Kijima N., et. al.: Molecular Classification of Medulloblastoma. Neurol Med Chir (Tokyo) 2016 Nov; 56: pp. 687-697.
  • 2. Patay Z., et. al.: Magnetic resonance imaging characteristics of WNT-subgroup pediatric medulloblastoma. AJNR Am J Neuroradiol 2015 Dec; 36: pp. 2386-2393.
  • 3. Perreault S., et. al.: MRI surrogates for molecular subgroups of medulloblastoma. AJNR Am J Neuroradiol 2014 Jul; 35: pp. 1263-1269.

MEDULLOBLASTOMA: GROUP 3

Key Points

Background

  • Prevalence: 25%

  • Histology: Classic, large cell/anaplastic

  • Prognosis: 5-year survival 50% (poor prognosis)

  • Demographics: Infants and children; M:F ratio 2:1

Imaging

  • Location: Midline (vermis, fourth ventricle)

  • Enhancement in majority of tumors

  • Higher risk of presentation with metastasis

REFERENCES

  • 1. Kijima N., et. al.: Molecular Classification of. Medulloblastoma. Neurol Med Chir (Tokyo) 2016 Nov; 56: pp. 687-697.
  • 2. Perreault S., et. al.: MRI surrogates for molecular subgroups of medulloblastoma. AJNR Am J Neuroradiol 2014 Jul; 35: pp. 1263-1269.

MEDULLOBLASTOMA: GROUP 4

Key Points

Background

  • Prevalence: 35% (most common)

  • Histology: Classic, large cell/anaplastic

  • Prognosis: 5-year survival 75% (intermediate prognosis)

  • Demographics: Infants, children, and adults; M:F ratio 3:1

Imaging

  • Location: Midline (vermis, fourth ventricle)

  • Less enhancement

  • Higher risk of presentation with metastasis

REFERENCES

  • 1. Kijima N., et. al.: Molecular Classification of Medulloblastoma. Neurol Med Chir (Tokyo) 2016 Nov; 56; pp. 687-697.
  • 2. Perreault S., et. al.: MRI surrogates for molecular subgroups of medulloblastoma. AJNR Am J Neuroradiol 2014 Jul; 35: pp. 1263-1269.

PILOCYTIC ASTROCYTOMA

Key Points

Background

  • WHO grade 1

  • Accounts for 25% to 35% of pediatric posterior fossa tumors

  • Most tumors are sporadic in origin. Most tumors have the BRAF gene mutation leading to activation of the RAS/ERK/MAPK pathway

  • Neurofibromatosis type I associated with increased risk of pilocytic astrocytoma (typically optic gliomas; rarely posterior fossa)

  • 95% 5-year survival; prognosis dependent on extent of resection

  • Location: Cerebellar hemispheric (most common) or posterior fossa midline, optic pathway/hypothalamus, thalamus and cerebral hemisphere

Imaging

CT

  • Fluid density cysts and isodense or hypodense solid portion; dominant cyst with small iso- to hypodense solid component (most common); may have a small cystic component or entirely solid.

  • Calcifications; hemorrhage is uncommon at presentation.

MRI

  • Solid and cystic (commonly a cyst and nodule pattern ); well-circumscribed; fluid signal intensity or complex fluid signal intensity cystic component; T1W-hypointense, T2W-hyperintense solid component with intense enhancement; cyst wall may enhance but can be reactive rather than indicate tumor presence

  • Usually ADC hyperintense compared to normal brain; ADC values >1.4 × 10 3 mm 2 /s

  • Uncommonly metastasize, but possible

Advanced Imaging

  • MR perfusion: Variable CBF and CBV; often leaky blood-brain barrier which can lead to a T1 leakage pattern on DSC perfusion images characterized by the signal intensity rising above baseline after the contrast bolus has arrived

  • MRS: Aggressive metabolite pattern with ↑ choline and lactate, ↓ NAA and creatine. Can be misleading to diagnosis of a high-grade glioma

REFERENCES

  • 1. Plaza M.J., et. al.: Conventional and advanced MRI features of pediatric intracranial tumors: posterior fossa and suprasellar tumors. AJR Am J Roentgenol 2013 May200; pp. 1115-1124.
  • 2. Borja M.J., et. al.: Conventional and advanced MRI features of pediatric intracranial tumors: supratentorial tumors. AJR Am J Roentgenol 2013 May; 200: pp. W483-W503.
  • 3. Camilo J., et. al.: Primary neoplasms of the pediatric brain. Radiol Clin North Am 2019 Nov; 57: pp. 1163-1175.
  • 4. Ohkaki H., et. al.: Population-based studies on incidence, survival rates, and genetic alterations in astrocytic and oligodendroglial gliomas. J Neuropathol Exp Neurol 2005; 64: pp. 479-489.
  • 5. Rumboldt Z., et. al.: Apparent Diffusion Coefficients for Differentiation of Cerebellar Tumors in Children AJNR. Am J Neuroradiol 2006 Jun-Jul; 27: pp. 1362-1369.

EPENDYMOMA

Key Points

Background

  • WHO grade 2–3

  • Accounts for approximately 20% of pediatric posterior fossa tumors

  • Molecular subgroups

    • EPN_PFA (80%): Infants and young children; poor prognosis ; reduced trimethylation of H3K27

    • EPN_PFB: Older children and adolescents; better prognosis; increased levels of trimethylation of H3K27

    • Subependymoma

  • Neurofibromatosis type 2 (NF-2)–associated with increased risk of ependymoma

  • 7-year survival is 65%; prognosis dependent on extent of resection, tumor grade, and molecular subtype

  • Location: Floor of the fourth ventricle with projections of tumor and through the foramen Magendie and foramina of Luschka

Imaging

CT

  • Isodense-hyperdense; well-defined; calcifications more common than any other posterior fossa tumors; small cysts and hemorrhage may occur

MRI

  • Well-circumscribed; T1W hypointense, T2W iso- to hyperintense; variable enhancement

  • Intermediate ADC signal (usually isointense compared to normal brain ) between medulloblastoma and pilocytic astrocytomas with ADC values ∼1.0-1.3 × 10 3 mm 2 /s

  • Metastasis uncommon, but increased risk with higher grade, and younger age

Advanced Imaging

  • MRS: ↑ Myoinositol , choline, and lactate; ↓ NAA

  • MR perfusion: ↑ CBF and CBV

REFERENCES

  • 1. Plaza M.J., Borja M.J., Altman N., Saigal G.: Conventional and advanced MRI features of pediatric intracranial tumors: posterior fossa and suprasellar tumors. AJR Am J Roentgenol 2013 May; 200: pp. 1115-1124.
  • 2. Camilo J., et. al.: Primary neoplasms of the pediatric brain. Radiol Clin North Am 2019 Nov; 57: pp. 1163-1175.
  • 3. Rumboldt Z., et. al.: Apparent Diffusion Coefficients for Differentiation of Cerebellar Tumors in Children. AJNR. Am J Neuroradiol 2006 Jun–Jul; 27: pp. 1362-1369.
  • 4. Vijay Ramaswamy, et. al.: Therapeutic Impact of Cytoreductive Surgery and Irradiation of Posterior Fossa Ependymoma in the Molecular Era: A Retrospective Multicohort Analysis. J Clin Oncol 2016 Jul 20; 34: pp. 2468-2477.
  • 5. Rezai A.R., et. al.: Disseminated ependymomas of the central nervous system. J Neurosurg 1996 Oct; 85: pp. 618-624.

ATYPICAL TERATOID RHABDOID TUMOR

Key Points

Background

  • WHO grade 4

  • SMARCB1 mutations

  • Rhabdoid tumor predisposition syndrome (RTPS) associated with increased risk of ATRT

  • Dismal prognosis in patients <3 years of age (most common age group is <3 years)

  • Location: Cerebellar, vermian/fourth ventricular , supratentorial (older patients)

Imaging

CT

  • Hyperdense heterogeneous mass, small cysts, necrosis, hemorrhage, and calcification may occur

MRI

  • Well-circumscribed heterogeneous mass, T1W isointense, T2W isointense, variable enhancement, small cysts, necrosis, hemorrhage and calcification

  • Restricted diffusion similar to other embryonal tumors

  • Metastasis common at presentation (>20%)

Advanced Imaging

  • MR perfusion: ↑ CBF and CBV

  • MRS: Aggressive metabolite pattern with ↑ choline, lipid and lactate; ↓ NAA

REFERENCES

  • 1. Plaza M.J., et. al.: Conventional and advanced MRI features of pediatric intracranial tumors: posterior fossa and suprasellar tumors. AJR Am J Roentgenol 2013 May; 200: pp. 1115-1124.
  • 2. Rumboldt Z., et. al.: Apparent Diffusion Coefficients for Differentiation of Cerebellar Tumors in Children. AJNR. Am J Neuroradiol 2006 Jun-Jul; 27: pp. 1362-1369.
  • 3. Tekautz T.M., et. al.: Atypical Teratoid/Rhabdoid Tumors (ATRT): Improved Survival in Children 3 Years of Age and Older With Radiation Therapy and High-Dose Alkylator-Based Chemotherapy. J Clin Oncol 2005 Mar 1; 23: pp. 1491-1499.
  • 4. Meyers S.P., et. al.: Primary Intracranial Atypical Teratoid/Rhabdoid Tumors of Infancy and Childhood: MRI Features and Patient Outcomes. AJNR Am J Neuroradiol 2006 May; 27: pp. 962-971.

EMBRYONAL TUMOR WITH MULTILAYERED ROSETTES

Key Points

Background

  • Embryonal tumor with multilayered rosettes (ETMR) is a WHO grade 4 tumor recently classified in 2016 as tumors with amplification or gain of the C19MC region on chromosome 19 (19q13.42). This now includes tumors previously known as embryonal tumor with abundant neuropil and true rosettes (ETANTR), ependymoblastoma, and in some cases medulloepithelioma

  • Median age at presentation <3 years

  • Poor prognosis; median survival is 8 months

  • Location: Both supratentorial (cerebral hemisphere) and infratentorial locations (along the tentorium, cerebellar vermis, fourth ventricle, and brainstem)

Imaging

CT

  • Variable density with 50% hyperdense; hemorrhage and calcification (67%)

MRI

  • Large, well-circumscribed, homogeneous, T2W hyperintense, minimal enhancement, and minimal to no surrounding edema

  • Restricted diffusion similar to other embryonal tumors (median ADC 728 mm 2 /s)

  • Leptomeningeal disease uncommon

Advanced Imaging

  • MR perfusion:

    • ↓ CBF (median 30 mL/min/100g; unusual for high-grade tumors and different than what is seen typically with ATRT and medulloblastoma)

    • ↑ CBV (maximal rCBV 3.5–5.8; mean rCBV 1.7–2.7)

  • MRS: Limited data indicate ↑ choline and taurine

REFERENCE

  • 1. Dangouloff-Ros V., Tauziède-Espariat A., Roux C.J., et. al.: CT and Multimodal MR Imaging Features of Embryonal Tumors with Multilayered Rosettes in Children. AJNR Am J Neuroradiol. 2019 Apr; 40: pp. 732-736.

DYSPLASTIC CEREBELLAR GANGLIOCYTOMA

Key Points

Background

  • Also known as Lhermitte-Duclos. WHO grade 1

  • May be associated with hemimegalencephaly or hemihypertrophy syndromes

  • Cowden syndrome associated with increased risk of dysplastic cerebellar gangliocytoma

  • Location: Cerebellar hemisphere; may extend into vermis

Imaging

CT

  • Ill-defined hypodense mass; hemorrhage and calcification may occur

MRI

  • Well-circumscribed heterogeneous striated mass “enlarging the regional cerebellum,” also known as “corduroy appearance” with significant mass effect. Bands of alternating T2W hyper- and hypointense signal; areas of cystic change; most do not enhance but may have regions of enhancement; hemorrhage and calcification may occur.

  • Lack of restricted diffusion.

Advanced Imaging

  • MR perfusion: Regions of ↑ rCBV

  • MRS: ↑ Lactate; ↓ NAA and myoI

REFERENCES

  • 1. Klisch J., et. al.: Lhermitte-Duclos disease: assessment with MR imaging, positron emission tomography, single-photon emission CT, and MR spectroscopy. AJNR Am J Neuroradiol 2001; 22: pp. 824-830.
  • 2. Dhamija R., et. al.: Updated Imaging Features of Dysplastic Cerebellar Gangliocytoma. J Comput Assist Tomogr 2019 Mar/Apr; 43: pp. 277-281.

MEDULLARY GLIOMA

Key Points

Background

  • Low-grade : WHO grade 1 (dorsally exophytic), WHO grade 2 (diffuse)

  • Three subtypes:

    • Dorsally exophytic (pilocytic astrocytoma, ganglioglioma)

    • Diffuse infiltrating (fibrillary astrocytoma)

    • NF -1–associated focal gliomas (pilocytic astrocytoma)

  • Prognosis better in dorsally exophytic and NF-1–associated gliomas compared to diffuse infiltrating

  • Location: Medulla or cervicomedullary

Imaging

CT

  • Hypodense mass

MRI

  • Dorsally exophytic

    • Well -circumscribed, multilobulated T1W hypointense, T2W hyperintense, variable enhancement, and small cysts

    • Lack of restricted diffusion

    • Dorsally exophytic with involvement of the medulla

  • Diffuse infiltrating (fibrillary astrocytoma)

    • Less well -defined T1W hypointense, T2W hyperintense, and variable enhancement

    • Lack of restricted diffusion

    • Infiltrative expansion of the medulla

  • NF-1–associated focal gliomas (pilocytic astrocytoma)

    • Focal , and usually small; well-defined; T1W hypointense, T2W hyperintense, and variable enhancement

Advanced Imaging

  • MR Perfusion: decreased CBV and CBF

  • MRS: varies based on histology

REFERENCE

  • 1. McAbee J.H., et. al.: Cervicomedullary tumors in children. J Neurosurg Pediatr 2015 Oct; 16: pp. 357-366.

DIFFUSE MIDLINE GLIOMA (DIFFUSE INTRINSIC PONTINE GLIOMA)

Key Points

Background

  • High-grade: WHO grade 3–4

  • H3K27M mutation (histone H3 lysine27-to-methionine mutation) is present in 70%

  • Term DIPG (diffuse intrinsic pontine glioma) no longer officially is used

  • The pons is the most common location of brainstem tumors

  • Signs and symptoms include hyperreflexia, ataxia, and cranial neuropathies (particularly abducens palsy). Behavior and cognitive changes also may occur

  • Poor prognosis. Median survival is 9 to 11 months

  • Location: Midline pons but may extend into the cranial and caudal brainstem and even into the cerebellum and supratentorial brain at end stage

Imaging

CT

  • Hypodense expansile mass of the pons

MRI

  • Poorly circumscribed T1W hypointense, and T2W hyperintense infiltrative expansile mass; mostly nonenhancing . May have regions of focal or cystic necrotic peripheral enhancement. Commonly effaces the prepontine cistern and encases or partially encases the basilar artery

    • Lack of restricted diffusion, although higher-grade components, which commonly enhance, may have restricted diffusion

    • End stage may metastasize or rarely at presentation

Advanced Imaging

  • MR perfusion: Typically, low CBF and CBV at presentation with exception of enhancing areas; postradiotherapy demonstrates increased CBF

  • MRS: ↑ Elevated choline, lactate & lipid; ↓ low NAA

REFERENCES

  • 1. Camilo J., et. al.: Primary neoplasms of the pediatric brain. Radiol Clin North Am 2019 Nov; 57: pp. 1163-1175.
  • 2. Brandão L.A.: Pediatric brain tumors. Neuroimaging Clin N Am 2013 Aug; 23: pp. 499-525.

TECTAL GIOMA

Key Points

Background

  • WHO grade 1 (most commonly pilocytic astrocytoma)

  • Obstruction of cerebral aqueduct leads to hydrocephalus and presentation

  • Most managed with third ventriculostomy

  • Excellent prognosis

  • Location: Tectal plate; may extend into the adjacent tegmentum and thalami

Imaging

CT

  • Hypodense expansile mass of the tectum

MRI

  • Well-defined T1W hypointense, and T2W hyperintense expansile tectal mass; often nonenhancing, but may enhance. Effaces the cerebral aqueduct

  • Lack of restricted diffusion

Advanced Imaging

  • MR Perfusion: decreased CBV and CBF

  • MRS: not routinely performed

REFERENCES

  • 1. Bowers D.C., et. al.: Tectal gliomas: natural history of an indolent lesion in pediatric patients. Pediatr Neurosurg 2000 Jan; 32: pp. 24-29.
  • 2. Liu A.P.Y., et. al.: Tectal glioma as a distinct diagnostic entity: a comprehensive clinical, imaging, histologic and molecular analysis. Acta Neuropathol Commun 2018 Sep 25; 6: pp. 101.

CEREBRAL HEMISPHERE TUMORS

DYSEMBRYOPLASTIC NEUROEPITHELIAL TUMOR

Key Points

Background

  • WHO grade 1

  • Peak incidence in the second decade of life; affects more M>F

  • Presentation with intractable seizures

  • Mixed glioneuronal tumor that may be associated with focal cortical dysplasia (type IIIB)

  • 5-year survival >95%

  • Location

    • Hemispheric tumor in the cortex and subcortical white matter, especially the temporal lobe, but they can occur anywhere. Rarely arise in the brainstem, cerebellum, and basal ganglia.

    • Nearly always solitary; rarely multifocal

Imaging

CT

  • Well-defined hypodense mass without hemorrhage. Calcifications may occur. Small lesions may be entirely missed. Scalloping of the overlying calvarium can occur and suggests slow growing and lengthy presence of the mass.

MRI

  • T1W hypointense, T2W hyperintense “bubbly” lesion due to cystic or microcystic appearance of the tumor. Nodular or diffuse appearance may also be seen. Peripheral rim of T2 FLAIR signal may be present. Some have a triangular configuration, especially larger mass lesions.

  • Most commonly nonenhancing but up to one-third will have small areas of nodular, ring-like, or heterogeneous enhancement. Absent peritumoral edema and little to no mass effect.

  • Facilitated diffusion.

Advanced Imaging

  • MR perfusion: ↓ rCBV

  • MRS: normal or ↑ myoI

REFERENCES

  • 1. O’Brien D.F., et. al.: The Children’s Cancer and Leukaemia Group guidelines for the diagnosis and management of dysembryoplastic neuroepithelial tumours. Br J Neurosurg 2007; 21: pp. 539-549.
  • 2. Stanescu Cosson R., et. al.: Dysembryoplastic neuroepithelial tumors: CT, MR findings and imaging follow-up: a study of 53 cases. J Neuroradiol 2001; 28: pp. 230-240.
  • 3. Luzzi S., et. al.: Dysembryoplastic Neuroepithelial Tumors: What You Need to Know. World Neurosurg 2019; 127: pp. 255-265.
  • 4. Fellah S., et. al.: Epileptogenic brain lesions in children: the added-value of combined diffusion imaging and proton MR spectroscopy to the presurgical differential diagnosis. Childs Nerv Syst 2012; 28: pp. 273-282.
  • 5. Zamora C., et. al.: Supratentorial Tumors in Pediatric Patients. Neuroimaging Clin N Am 2017 Feb; 27: pp. 39-67.
  • 6. Nguyen H.S., et. al.: Dysembryoplastic Neuroectodermal Tumor: An Analysis from the Surveillance, Epidemiology, and End Results Program, 2004-2013. World Neurosurg 2017; 103: pp. 380-385.

GANGLIOGLIOMA

Key Points

Background

  • WHO grade 1 (low grade), grade 2 (atypical), and grade 3 (anaplastic). May progress to grade 4.

  • Median age of 12 years; male predominance

  • Neoplastic neuronal elements and astrocytes

  • Similar imaging appearance to gangliocytomas, pilocytic astrocytomas, oligodendrogliomas, and DNETs

  • 85% associated with seizures ; reported to be the most common cause of chronic temporal lobe epilepsy

  • Survival 98% at 7.5 years

  • Location

    • Temporal , especially mesial temporal followed by frontal. May rarely occur intraventricular or in brainstem, cerebellum, or spinal cord. Cerebellar gangliogliomas are reported to have unusual associated atrophy of the ipsilateral cerebellar hemisphere.

Imaging

CT

  • Small lesions will be easily missed by CT. Hypodense mass; calcification is common; hemorrhage is uncommon

MRI

  • Variable appearance

  • Typically, T1W hypointense and T2W hyperintense variably enhancing solid mass with or without cysts. Lesions within the mesial temporal lobe; however, may be primarily solid, poorly delineated with little enhancement.

  • Increased ADC ; higher-grade lesions may have lower ADC

Advanced Imaging

  • MR perfusion: ↓ CBV and CBF

  • MRS: ↓ NAA, ↑ myoI

REFERENCES

  • 1. Zamora C., et. al.: Supratentorial Tumors in Pediatric Patients. Neuroimaging Clin N Am 2017 Feb; 27: pp. 39-67.
  • 2. Zaky W., et. al.: Ganglioglioma in children and young adults: single institution experience and review of the literature. J Neurooncol 2018; 139: pp. 739-747.
  • 3. Adachi Y., et. al.: Gangliogliomas: Characteristic imaging findings and role in the temporal lobe epilepsy. Neuroradiology 2008; 50: pp. 829-834.
  • 4. Raybaud C.: Cerebral hemispheric low-grade glial tumors in children: preoperative anatomic assessment with MRI and DTI. Childs Nerv Syst 2016; 32: pp. 1799-1811.

OLIGODENDROGLIOMA

Key Points

Background

  • WHO grade 2 (low grade) and grade 3 (anaplastic)

  • 1% to 3% of pediatric CNS neoplasms

  • Rare entity in children compared to adults ; peak incidence is fifth to sixth decade

  • Uncommon to have 1p19q deletion or IDH1 mutation which is different from adult patients; MGMT promoter methylation is similar to adult patients

  • Excellent prognosis; 5-year survival 95%

  • Location

    • Typically, hemispheric, cortical and subcortical tumor. Frontal lobe is most common followed by parietal and temporal lobe. Rarer locations include brainstem, cerebellopontine angle, optic nerve, and spinal cord.

Imaging

CT

  • Small lesions will be easily missed by CT. Hypodense peripheral mass; calcification may be seen but less common than in adults; hemorrhage is uncommon

MRI

  • Well-defined T1W hypointense and T2W hyperintense; nonenhancing to minimally enhancing solid mass with or without cysts; can also be poorly delineated with little enhancement.

  • Increased ADC, even in high-grade lesions

Advanced Imaging

  • MR perfusion: Variable but potential for ↑ CBV/CBF

  • MRS: ↑ Choline, lactate, and lipid in higher-grade lesions and thus may be more helpful than dynamic susceptibility perfusion imaging

REFERENCES

  • 1. Li Y.X., et. al.: Oligodendrogliomas in pediatric and teenage patients only rarely exhibit molecular markers and patients have excellent survivals. J Neurooncol 2018; 139: pp. 307-322.
  • 2. Raybaud C.: Cerebral hemispheric low-grade glial tumors in children: preoperative anatomic assessment with MRI and DTI. Childs Nerv Syst 2016; 32: pp. 1799-1811.
  • 3. Zamora C., et. al.: Supratentorial Tumors in Pediatric Patients. Neuroimaging Clin N Am 2017 Feb; 27: pp. 39-67.
  • 4. Brandão L.A., et. al.: Pediatric brain tumors. Neuroimaging Clin N Am 2013 Aug; 23: pp. 499-525.

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