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Glioblastoma Multiforme

 

Glioblastoma multiforme, the most malignant of the neuroepithelial neoplasms, is characterized by cellular pleomorphism, numerous mitotic figures, and often multinucleated giant cell. Proliferation of the vascular endothelium is seen as well as areas of necrosis with circumjacent pseudopalisading of the neoplastic cells.It can appear as either a well- circumscribed globular mass or a more diffuse mass lesion. The cut surface reveals necrosis, fatty degeneration, and hemorrhage. Hemorrhages have been found in 40%, with necrosis in up to 52% of the cases. The tumor is usually solid, although cysts may be present. Rarely the tumor consists of a solitary cyst and mural nodule.

Grading according to degree of malignancy was first proposed in 1949. In this classification, astrocytomas and glioblastomas represent different grades of malignancy of the same tumor. Grade I tumors, typically slow growing, are characterized by most cells having normal characteristics, and few mitotic features. Endothelial proliferation is absent. Grade II tumors, previously designated "astroblastomas," are characterized by an increased number of cells with polymorphic nuclei in mitoses. There is no clear line of demarcation from normal tissue. Grade III tumors represent anaplastic astrocytomas and Grade IV tumors represent the typical glioblastoma multiforme, characterized by cellular pleomorphism, vascular proliferation, mitoses, and multinucleated giant cells.

Glioblastoma multiforme constitutes approximately 7% of childhood intracranial neoplasms. The overall male to female ratio in children is 3:2. In adults, glioblastomas are noted most frequently in the frontal lobe with the temporal lobe second in frequency. Childhood glioblastomas of the cerebral hemispheres are also located most often in the frontal lobe; with the second most frequent site being the parietal lobe. Primary glioblastoma of the spinal cord in childhood is rare.

Glioblastoma multiforme in children appears to have two characteristic courses, each of which is related to the location of the tumor. Glioblastomas of the brainstem, a more primitive part of the central nervous system, occur at a younger age and have a shorter mean survival relative to those of the cerebral hemispheres. Glioblastoma multiforme of the cerebral hemisphere, a more highly developed part of the central nervous system, is characterized by onset in older children (13 years) and by a longer mean survival.

Headache is the most common complaint and papilledema the most common physical finding in children with hemispheric glioblastoma. Seizures are noted in up to one third of the children. Survival rates in patients with glioblastoma multiforme is uniformly poor. In studies of children treated with surgery and intracranial radiation, only one third of the children are alive one year after diagnosis. Survival of children with glioblastoma multiforme of either of the cerebral hemispheres or the brainstem has significantly increased since the advent of dexamethasone therapy. Presently therapy consists of surgery plus combination chemotherapy (8 in 1).

In summary it can be said that glioblastoma multiforme behaves similarly in both children and adults. The course of intracranial glioblastomas in children is more rapidly fatal than that of other similarly situated gliomas in childhood. While the overall survival rate is very poor in patients with a glioblastoma multiforme, intensive chemotherapy with surgical resection does offer some hope in increasing survival time among children.