**Germ cell tumors**


#### **Tumors of the sellar region**


#### **Metastatic tumors**

Modified from the WHO Classification of Tumors of the CNS, 2007 [7].

## **5. Clinical manifestations**

The most common presenting symptoms of pediatric brain tumours are due to increased intracranial pressure. Headache and vomiting are two well-known symptoms associated with elevated intracranial pressure. Other signs, which reflect the increase in intracranial pressure, include drowsiness, confusion, nausea, sixth nerve palsy, papilledema, generalized seizures, and cognitive impairment. Focal signs and symptoms reflect the effect of the tumor on specific structures [8].

### **6. Radiological diagnosis**

The features that play an important role in establishing the diagnosis are the age of the patient, location of the tumor and the imaging characteristics. Supratentorial tumors are more common in neonates and infants up to 2 years old, whereas infratentorial tumors are more common in children older than 2 years. Although some tumors may be found both supra- and infratentorially. Tumors that are considered mostly supratentorial and intraaxial include astrocytomas, such as diffuse astrocytoma, anaplastic astrocytoma, pleomorphic xanthoastrocytoma (PXA), subependymal giant cell astrocytoma (SEGA), and glioblastoma multi-forme (GBM); oligodendrocytoma; primitive neuroectodermal tumor (PNET); dysembryo-plastic neuroepithelial tumor (DNET); ganglioglioma; and desmoplastic infantile ganglioglioma. Some supratentorial extraaxial masses include arachnoid cysts, pineal region masses, and choroid plexus tumors.

Imaging is an important aspect in the management of patients with brain tumors. Imaging workup is largely based upon CT and MRI of the lesion. The technical development of CT and MRI methods has greatly enhanced brain tumor detection and sophisticated neuroimaging offers extra data by determining the metabolism and physiology of these lesions, which helps to diagnose and monitor brain neoplasms [9].

### **7. Computed tomography (CT)**

CT scan plays an important role in establishing diagnosis of brain tumours. It can detect both blood and calcification. But some tumors, particularly tumors of

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*An Overview of Pediatric CNS Malignancies DOI: http://dx.doi.org/10.5772/intechopen.88189*

**7.1 MRI**

infiltrative tumor.

**7.2 Perfusion MRI**

intracranial masses [11].

**7.4 Magnetic resonance spectroscopy**

**7.5 Positron emission tomography (PET)**

high-grade gliomas [14].

**7.6 Cerebral fluid analysis**

treatment favor edema and postsurgical changes [13].

radiotracer in determining the grade of brain tumors.

**7.3 Functional MRI**

tumours [12].

the white matter, can be missed on CT neuroimaging [10].

fluid-attenuated inversion recovery (FLAIR) sequences.

the brainstem, cerebellum, and suprasellar region as well as infiltrative tumors of

It is the standard of care in children for imaging of suspected brain tumours. The most useful imaging studies are T1-weighted sagittal images, gadolinium (Gd)-enhanced and unenhanced T1 axial images, T2-weighted axial images, and

T1 images usually are better at demonstrating anatomy and areas of contrast enhancement. T2 and FLAIR images are more sensitive for detecting edema and

It plays an important role In differentiating low-grade tumors from high-grade tumors. It evaluates several hemodynamic parameters including cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT); however, CBV has been shown to be the most useful parameter for the evaluation of

It detects functional areas of the brain by identifying areas of brain activation which have increased blood flow and changes in cerebral metabolism. It is used to determine the extent of resection as it can prevent any functional compromise. It is essential for planning function-preserving surgery in patients with brain

It is useful in the evaluation of brain tumors in pediatric patients by helping determine the diagnosis, grade, and extent of the tumor. MRS can also differentiate radiation necrosis from tumor recurrence because normal metabolite levels after

PET has clearly defined roles in primary brain tumor imaging. The FDG uptake of high-grade gliomas is more as compared with low-grade or well-differentiated neoplasms, and FDG-PET can be useful in making a distinction between low- and

A few limitations of FDG-PET as a cerebral imaging agent are that normal brain tissue has high physiologic glucose metabolic rate producing a high FDG uptake which may mask smaller lesions. Another issue is in the detection of tumors with only modest increases in glucose metabolism, such as low-grade tumors which may be difficult to interpret [15]. 18F-fluoroethyl-L-thyrosin (18F-FET) is a promising

Chemistry and cytology of the cerebral fluid are used to determine the spread of

the tumor. Findings may be important in subsequent treatment approaches.

the brainstem, cerebellum, and suprasellar region as well as infiltrative tumors of the white matter, can be missed on CT neuroimaging [10].
