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tumour control, regardless of tumour grade. The incidence of spinal dissemination was significantly lower in locally controlled patients than in those with uncontrolled primary lesions (3.3% versus 9.5%) [35] .

cles than in the third ventricle. Myxopapillary ependymomas are typically and almost exclusively located in the conus – cauda equina – filum terminale region. Rarely, they have been observed in the upper spinal cord, in the lateral ventricles or in the brain parenchyma. Subependymomas are typically located in the fourth and in the lateral ventricles. Ependymoma appears as a well-circumscribed lesion with varying degrees of contrast enhancement, which is more pronounced in anaplastic tumours and can be absent in subependymomas, on either MRI or CT scanning. A cys- tic component, the presence of calcium, and intra-tumoural haemorrhage are occasionally observed, while oedema and brain infiltration are infrequent. Surgical exploration and biopsy are essential for the selection of appropriate treatment. 3.3. Diagnostic criteria

5. Prognosis

5.1. Natural history

Grades I–II tumours, which are slowly growing gliomas, disseminate infrequently to brain parenchyma, nerve roots, bones and CSF; they are sometimes asymptomatic and are found incidentally at autopsy [40] . Anaplastic ependymo- mas exhibit a more rapid growth pattern and are occasionally invasive. They may occasionally be the result of malignant progression from grade II tumours, and tend to spread into the CSF more frequently, particularly if located in the posterior fossa. Most reported series of ependymomas are retrospective and, include only a small number of patients, due to the low incidence of this tumour type. Moreover, these studies span several decades which hampers the interpretation of the results due to changes in grading systems and diagnostic and therapeutic policies, and with limited statistical power. Con- sequently, generally accepted prognostic factors are lacking. The prognostic significance of tumour grade is not universally accepted, most likely due to the varying definitions of anapla- sia [41–43] , to the large number (69%) of discrepancies between local pathology diagnosis and those reported on cen- tralised review [44] , and to the fact that classical histological features of anaplasia seem to be unrelated to the biologi- cal behaviour of ependymomas [40] . Another confounding factor is that most series fail to distinguish patients with malignant ependymomas from those with ependymoblas- tomas which have an especially poor prognosis. According to some authors, tumour grade is the most important deter- minant of prognosis [34,35,45–49] , whereas others did not find any correlation between survival and histologic grade suggesting that the outcome is influenced by anatomical loca- tion, which dictates resectability, rather than by pathological features [37,38,50–53] . The 5-year survival for patients with low-grade tumours ranges from 55% to 87%, whereas for anaplastic ependymomas it varies between 10% and 47% [34,39,47,54] . A direct correlation between age and better prognosis has been suggested. The small number of patients, the different definitions of paediatric age among series (rang- ing from 12 to 20 years), and the heterogeneity of histological grade and tumour location [34,49,54–57] between the com- pared groups preclude reliable conclusions. Ependymomas are uncommon in adults, and it is difficult to clearly assess outcome in a strictly adult population as most of the published series mainly relate to paediatric patients. Adult patients 5.2. Prognostic factors

4. Staging

4.1. Staging procedures

The staging work-up should include a careful history, physical examination and magnetic resonance imaging of the brain and the spinal cord. Examination of the CSF for cyto- logical evidence of malignancy is essential. The incidence of spinal seeding is 1.6% for supratentorial tumours, 9.7% for infratentorial lesions, 8.4–20% for high-grade tumours, and 2–4.5% for low-grade lesions [34,35] . The highest incidence is observed among high-grade infratentorial ependymomas.

4.2. Staging system

The UICC/AJC classification [36] is applied to all brain tumours and distinguishes between supratentorial and infratentorial locations. However, this classification is rarely used and the nodal and distant metastases categories very rarely occur in ependymomas.

4.3. Restaging procedures

Restaging should include all the diagnostic procedures that were positive at the time of diagnosis and of initial staging. Spinal seeding rate is consistently different among reported series, most likely due to different diagnostic cri- teria and whether either clinical or pathologic seeding was considered—the latter being almost 10 times more frequent than the former [37] . The most important determinants of the risks on spinal seeding are tumour grade and localisation [35] ; 0–12.5% of patients with high-grade supratentorial lesions developed spinal seeding, whereas 0–38%of those with high- grade infratentorial tumours developed spinal dissemination [33,35,38,39] . For low-grade tumours, 0–7% of patients with supratentorial lesions developed seeding compared with 0–40% for those with infratentorial lesions [33,35,37–39] . The incidence of spinal seeding was related directly to local