Tumors of the Posterior Fossa in Childhood and Adolescence

Abstract

Children with tumors of the posterior fossa are quite often referred to a radiotherapy department for some phase of management. Only a very few highly specialized institutions, however, have enough cases to permit evaluation of the effect of treatment and observation of the full course of the disease. As is well known, two features distinguish brain tumors of children from those of adults. The most significant is the higher percentage of gliomas in children. Figures range from 60 to 80 per cent for children and from about 40 to 60 per cent for adults. This difference is due to the greater frequency of cerebellar gliomas in children and to the infrequent occurrence of three common tumors usually found in adults; namely, meningiomas, acoustic neurinomas, and pituitary adenomas. The other important feature is that childhood neoplasms occur in the infratentorial region in about 65 to 75 per cent of the cases, whereas meningeal tumors of adults occur in the supratentorial region. Astrocytomas and medulloblastomas of children have a predilection for the infratentorial region (1, 2). To obtain a better orientation of the problem of posterior fossa tumors of childhood, we have reviewed our material from the years 1938 to 1960. These patients were seen in the Radiotherapy Department, Research and Educational Hospitals, University of Illinois, and of course are not the total census of brain tumors seen by this department. We have tried to correlate the clinical, diagnostic, and therapeutic aspects of the 67 children with posterior fossa tumors. Early in the study, it was noted that three rather distinct patterns were recognizable. Table I presents the number in each group with the histological diagnosis and anatomical site. Group I: The Medulloblastoma-Sarcoma In 19 cases the histological diagnosis was medulloblastoma of the cerebellum, and 6 of these children came to autopsy. Sarcoma was reported upon surgical biopsy in 14 children, of whom 5 were later autopsied. Since sarcoma of the cerebellum and leptomeninges is difficult to differentiate both clinically and histologically from medulloblastoma, these patients are in included in the medulloblastoma group. Thirteen of the 19 medulloblastomas occurred in white males, and the remaining 6 in females, 2 of whom were Negroes. The ages ranged from two to twenty years, with 10 patients under ten, giving a mean age of nine and three-tenths years. In 13 cases the tumor had originated in the midline or vermis of the cerebellum, in the remainder it extended into either hemisphere. The sarcoma division had an equal number of males and females, with a single Negro female. Their ages ranged from nineteen months to twenty years, with 9 patients under ten years, and a mean age of nine and eight-tenths years. Only 5 lesions were reported in the midline of the cerebellum.