ABSTRACT
Cerebral tumors are the commonest solid neoplasm affecting children, accounting for approximately 18% of childhood malignancy. The principal histological types of tumor are shown in Table 1; over 50% of these arise in the cerebellum or brain stem in contrast to adult brain tumors which largely occur in the cerebral hemispheres. A significant proportion of children’s brain tumors are composed of small round cells and can, therefore, give rise to potential difficulties in pathological diagnosis. Brain tumors may be situated in deep and highly strategic brain areas which means that the surgeon may only be able to provide a small amount of biopsy material and this may be mechanically deformed by, for example, squeeze artifact by biopsy rongeurs. In the past, biopsies were not attempted for certain deep-seated tumors, but now the use of more refined and accurate techniques such as CT directed stereotactic biopsy 1 and endoscopic biopsy 2 means that small amounts of tissue will be more increasingly available for the diagnosis of such lesions. In addition, increased use of the newer techniques for tumor resection such as laser and ultrasonic aspirator 2 means that the pathologist might be denied adequate amounts of tissue in certain cases. Incidence of Childhood Brain Tumors
%of total
Astrocytomas (low grade)
36
Astrocytomas (high grade)
10
Medulloblastomas
21
Ependymomas
10
Craniopharyngiomas
6
Pineal region tumors
2.5
Choroid plexus tumors
1.5
Others
13
Note: In children under 16 years.