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[Tumors of the posterior fossa in children].

INTRODUCTION
Primary tumours of the CNS form 20% of the neoplasias seen in children. They are the second commonest type of cancer seen in childhood, after leukemia. A significant proportion of paediatric cerebral tumours (> 50%) are intratentorial.


OBJECTIVE
To find the frequency and clinicopathological behavior of posterior fossa tumours in children seen at our hospital.


PATIENTS AND METHODS
From the hospital records, a descriptive, retrospective study was made of 112 children with tumours of the posterior fossa who were attended at the Institute of Neurology and Neurosurgery between January 1980 and December 1997. The variables: age, sex, clinical findings, site and extent of the tumour and its histological description were recorded. The mean, standard deviation, frequency distribution and chi-squared test were used, depending on the type of variable to be analyzed.


RESULTS
The age of the patients when the diagnosis was made was between 8 months and 15 years (mean = 8.32 years). The male/female ratio was 59/53 (1.1/1). The commonest site of the tumours was the cerebellum (58.9%). The predominant histological types were medulloblastoma (33.92%) and astrocytoma (19.64%) in the cerebellum, glioma in the brain stem (10.71%) and ependymoma in the i.v. ventricle (8.09%).


CONCLUSIONS
Endocranial hypertension and the cerebellar syndrome were the predominant clinical findings in medulloblastoma, cerebellar astrocytoma and ependymoma. In brainstem gliomas there was often involvement of several cranial nerves and long tracts.