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Image courtesy of Malik Muhammad Adil, MBBS.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

Contrast-enhanced magnetic resonance imaging (MRI) of the brain in an 8-year-old boy (shown) demonstrates an enhancing tumor of the left parietal lobe (arrow), with notable edema and midline shift. This finding is consistent with a high-grade or malignant tumor (an astrocytoma, in this case).

Brain tumors in children are classified according to the cell type from which they originate (ie, gliomas, neural tumors, nonneuroepithelial tumors, choroid plexus papilloma/carcinoma, germ cell tumors, mixed neuronal-glial tumors, meningeal tumors, and spinal cord tumors). They are also classified according to whether they are benign or malignant and their location (supratentorial or infratentorial). In adults, the vast majority of brain tumors are supratentorial; in children older than 1 year, about 50% are infratentorial.[1]

Pediatric brain tumors are mostly primary but can be metastatic as well. Primary brain tumors are the second most common group of malignancies affecting children (after leukemia) and are one of the leading causes of mortality. Benign gliomas, primitive neuroectodermal tumors (PNETs), and craniopharyngiomas account for the majority of brain tumors in this age group.

Image courtesy of Hina Dildar, MBBS.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

The typical clinical presentation consists of headache and vomiting. Focal neurologic signs (eg, hemiplegia, ataxia, cranial nerve palsies, and visual disturbances) may also be seen, along with seizures. Headache is the single most frequent presenting feature; it is most often secondary to raised intracranial pressure (ICP) and is exacerbated by postural changes, coughing, and straining. Fundoscopy may reveal papilledema. Imaging studies of the brain—computed tomography (CT) and MRI—remain the most important screening and diagnostic modalities.

Management centers on surgical resection, systemic chemotherapy, and adjuvant radiotherapy of the craniospinal axis. Radiotherapy plays a vital role and has been shown to improve clinical outcome and survival.

Images courtesy of Malik Muhammad Adil, MBBS.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

A 7-year-old boy presents with a history of headache and vomiting for 2 weeks, followed by altered mentation for 2 days. On examination, he has a Glasgow Coma Scale (GCS) score of 12. His cranial nerves are grossly intact. He moves all four extremities. Plantar reflexes are downgoing. Contrast-enhanced MRI shows a well-defined, lobulated, abnormal-signal-intensity mass lesion arising from the floor of the fourth ventricle. The lesion is iso- to hypointense on T1-weighted imaging (T1WI; left), is hyperintense on T2-weighted imaging (T2WI; right), and shows heterogeneous postcontrast enhancement. Obstructive hydrocephalus is visible as well. The radiologist reports the lesion as ependymoma.

Which of the following is the most common site of ependymoma in children?

  1. Third ventricle
  2. Lateral ventricles
  3. Fourth ventricle
  4. Cerebral aqueduct
Image courtesy of Malik Muhammad Adil, MBBS.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

Answer: C. Fourth ventricle.

Ependymoma arises from the ependymal cells that line the ventricles of the brain and the central canal of the spinal cord. It is the third most common pediatric brain tumor, accounting for approximately 10% of primary brain neoplasms. It is slightly more common in boys.[2] Nearly 70% of ependymomas are located infratentorially, within the fourth ventricle. The usual initial symptoms are headache, vomiting, and depressed level of consciousness as a result of hydrocephalus. On contrast-enhanced MRI, these lesions appear hypointense with T1WI and hyperintense with T2WI and exhibit heterogeneous postcontrast enhancement (shown). Cystic components may be present. Calcifications are seen in 50% of cases. These tumors can spread through cerebrospinal fluid (CSF) to other parts of the central nervous system (CNS). Biopsy and histopathologic evaluation are required for definitive diagnosis.

Image courtesy of Malik Muhammad Adil, MBBS.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

A 12-year-old boy presents with a history of progressive ataxia for 1 month and headache and vomiting for 1 week. On examination, he has a GCS score of 15. He has positive cerebellar signs and ataxia with a tendency to fall toward the right side. Contrast-enhanced CT shows a well-defined cystic lesion in the right cerebellum that appears hypodense, with perilesional vasogenic edema. An enhancing component is visible within the cyst. The results of histopathologic evaluation are consistent with juvenile pilocytic astrocytoma (JPA).

Which of the following is the most common site of JPA?

  1. Cerebellum
  2. Optic nerve
  3. Brainstem
  4. Hypothalamus
Image courtesy of Malik Muhammad Adil, MBBS.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

Answer: A. Cerebellum.

JPA is the most common astrocytoma in children.[3] It is most frequently located in the cerebellum; however, the optic nerves, the brainstem, the hypothalamus, or the cerebral hemispheres may also be involved. In most cases, JPA is a slow-growing tumor, a low-grade glioma with cyst formation that usually does not spread. Symptoms vary, depending on the size and location of the mass. As a rule, most of the symptoms of JPA result from increased ICP; they include headache, vomiting, ataxia, and vision abnormalities. Contrast-enhanced MRI demonstrates well-circumscribed cysts that appear hypointense on T1WI and hyperintense on T2WI and show variable postcontrast enhancement (arrow). Biopsy with histopathologic analysis reveals astrocytes with a fine fibrillary background. A characteristic microcystic component is often seen.

Image courtesy of Imran Wajid, MBBS, FCPS.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

A 5-year-old boy presents with a 5-day history of altered level of consciousness accompanied by headaches, seizures, nausea, and vomiting. He also has a history of personality change and decreased activity for several weeks. He has no focal weakness. On examination, his GCS score is 12, and he is drowsy and confused. Bilateral papilledema is apparent on fundoscopy. Cranial nerves are grossly intact. There is no motor weakness. Babinski testing elicits bilateral downgoing responses. Contrast-enhanced MRI reveals a large mass with a necrotic center in the right parietal lobe (shown) that appears hypointense on T1WI and hyperintense on T2WI, with mass effect and peritumoral edema, and exhibits postcontrast enhancement. The radiologist reports the lesion as glioblastoma multiforme (GBM).

Into which grade of astrocytoma does GBM fall?

  1. Grade I
  2. Grade II
  3. Grade III
  4. Grade IV
Image courtesy of Imran Wajid, MBBS, FCPS.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

Answer: D. Grade IV.

Astrocytoma is the most common CNS tumor in children and is divided into four major subtypes on the basis of histology: JPA (grade I), fibrillary/diffuse astrocytoma (grade II), anaplastic astrocytoma (grade III), and GBM (grade IV). GBM is the most common and most malignant form of astrocytoma.[4] Patients present with a short history of headache, vomiting, seizures, and slowly progressive motor weakness and cognitive decline. Neuroimaging (shown) reveals necrosis, mass effect, and enhancement with contrast administration. These tumors arise in the white matter of the cerebral hemispheres and involve the frontotemporal lobes, with infiltration into the contralateral hemisphere. Histologically, GBM is highly cellular with high proliferative activity. The prognosis is very poor, with a mortality of 90%.

Image courtesy of Malik Muhammad Adil, MBBS.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

A 5-year-old girl presents with lethargy, delayed milestones, and poor appetite. On examination, she is irritable and has bilateral facial paralysis and bulbar weakness. Contrast-enhanced MRI shows an expansile mass in the pons (arrow) that is isointense on T1WI and hyperintense on T2WI and fluid-attenuated inversion recovery (FLAIR) without postcontrast enhancement.

Which of the following is the most likely diagnosis?

  1. Brain abscess
  2. Tuberculoma
  3. Diffuse intrinsic pontine glioma (DIPG)
  4. GBM
Image courtesy of Medscape.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

Answer: C. Diffuse intrinsic pontine glioma (DIPG).

About 10-15% of all childhood brain tumors are located within the brainstem; the pons is the most commonly involved site, followed by the midbrain and the medulla.[5] DIPG is diagnosed during childhood by means of neuroimaging alone and has the worst prognosis of all the pediatric brain tumors: 80% of DIPGs are high-grade malignant masses. On histopathologic evaluation, most brainstem gliomas are infiltrating astrocytomas (shown).

Image courtesy of Malik Muhammad Adil, MBBS.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

A 3-and-a-half-year-old girl presents with a history of loss of vision, first in the left eye and then in the right eye. On examination, café-au-lait pigmentations are visible on her body. Vision in the left eye is reduced to finger counting, and she has complete blindness in the right eye. Fundoscopy reveals swelling in the optic nerve head. The family history is positive for epilepsy and skin lesions. MRI (shown) yields findings consistent with bilateral optic nerve glioma.

Which of the following is the most likely diagnosis?

  1. Tuberous sclerosis
  2. Neurofibromatosis type 1 (NF-1)
  3. Fungal infection
  4. CNS tuberculosis
Image courtesy of Medscape.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

Answer: B. Neurofibromatosis type 1 (NF-1).

NF-1 is a neurocutaneous disorder characterized by pigmented skin lesions (shown)—typically, café-au-lait spots.[6] Optic pathway tumors are a common manifestation; these may be prechiasmal, chiasmal, or postchiasmal and can result in visual loss and blindness. Neurologic involvement can also be seen in the form of CNS tumors (eg, gliomas or glioblastomas), epilepsy, and mental retardation. Skeletal involvement is present in 40% of cases of NF-1.

Other commonly seen skin lesions include neurofibromas, axillary freckles, and inguinal freckles. Lisch nodules may be present in the iris. These are hamartomas that often are identified only through slit-lamp examination by an ophthalmologist. Neurofibromas may be discrete or plexiform.

Images courtesy of Malik Muhammad Adil, MBBS.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

A 10-year-old boy presents with a 5-month history of ataxia and falls. On examination, he has positive cerebellar signs with gait ataxia. Contrast-enhanced MRI shows an enhancing cerebellar mass.

Which of the following is the most common malignant brain tumor in children?

  1. GBM
  2. Choroid plexus carcinoma
  3. Medulloblastoma
  4. Optic nerve tumor
Image courtesy of Medscape.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

Answer: C. Medulloblastoma.

Medulloblastoma, the most common malignant pediatric brain tumor,[7] accounts for 10-20% of primary CNS neoplasms in children and 40% of all posterior fossa tumors. It is invasive and originates primarily from the cerebellar vermis. It can rapidly spread to involve the cerebellar hemisphere, brainstem, and cervical spine. Contrast-enhanced MRI of the brain must be performed in all cases, along with imaging of the spine to screen for metastasis. Histopathologic evaluation is diagnostic and reveals undifferentiated cells with basophilic nuclei (arrows). Standard treatment consists of surgery followed by radiotherapy of the craniospinal axis and chemotherapy.

Image courtesy of Malik Muhammad Adil, MBBS.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

A 10-year-old girl presents with complaints of headache and vomiting followed by loss of consciousness and right-side weakness. MRI of the brain reveals a supratentorial PNET (arrow).

Which of the following is the most common site of cranial PNET?

  1. Cerebellum
  2. Brainstem
  3. Cerebral cortex
  4. Spinal cord
Image courtesy of Medscape.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

Answer: A. Cerebellum.

PNETs are malignant tumors that arise from neuroectoderm.[8] Cranial PNETs are most likely to be found in the cerebellum. Histopathologic evaluation reveals characteristic nuclear FLI-1 staining (shown).

Image courtesy of Malik Muhammad Adil, MBBS.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

A 10-year-old boy presents with headache, anorexia, nausea, and generalized weakness. MRI of his brain reveals a sharply demarcated, fluid-filled suprasellar mass (arrow). His hormone profile shows panhypopituitarism. Which of the following is the most likely diagnosis?

  1. Brain abscess
  2. Tuberculoma
  3. Craniopharyngioma
  4. GBM
Image courtesy of Medscape.

Pediatric Brain Tumors: Imaging Matters

Sumaira Nabi, MBBS, FCPS Neurology | January 17, 2023 | Contributor Information

Answer: C. Craniopharyngioma.

Craniopharyngioma is a benign neuroepithelial tumor thought to arise from the craniopharyngeal duct remnant. It constitutes 15% of supratentorial tumors and is usually seen in boys between the ages of 10 and 14 years. A second peak incidence is noted in decades 4-6. There are two histologic variants: The one found in children is mostly adamantinomatous craniopharyngioma (shown), a complex epithelial lesion with distinctive morphologic features. Patients present with headache, visual impairment, and features suggestive of pituitary hormonal dysfunction.

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