Original articlesKaryotype Studies in 18 Ependymomas with Literature Review of 107 Cases
Introduction
Ependymomas, a subclass of gliomas, arise from the ependymal layer of the brain and, less often, the spinal cord. They occur predominantly in children and young adults, where they account for up to 10% of intracranial tumors. The posterior fossa is the most common site in both adults and children [1]. The tumors are often slow-growing with marked variation in histology 2, 3. Though anaplastic features may be present, histologic classifications have been unreliable predictors of prognosis in this subclass of tumors 4, 5. Therefore, cytogenetic studies were analyzed in an attempt to correlate tumor karyotypes with clinical outcome.
The most consistent chromosome abnormality in both adult and pediatric ependymomas has been monosomy 22 or structural abnormality 22q, identified in approximately one third of Giemsa-banded cases with abnormal karyotypes. Chromosome 22 abnormalities, however, are seen in a number of different brain tumors 6, 7, 8, 9.
Cytogenetic studies are presented in 17 cases of pediatric brain ependymomas and 1 case of pediatric ependymoblastoma. Karyotypes from both primary tumor and nude mouse (NM) passages were analyzed in 5 cases. We have also reviewed the karyotypes of 107 published cases of banded cytogenetic studies from pediatric and adult ependymomas or ependymoblastomas 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38 to look for any distinctive pattern of abnormalities.
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Material and methods
The 18 cases of ependymomas, including 1 case of ependymoblastoma (Table 1), were G-banded chromosome analyses studied from 1987 to 1996 at Cincinnati Children's Hospital. Patient number 13 Table 1, Table 2 was diagnosed and received irradiation at another medical center, and was transferred to our hospital at the time of recurrence. Tumors were classified according to standard histopathologic criteria [39].
Primary tumor or that from NM passage was received in sterile medium. Xenografts in NM
Results
From 1987 to 1996, 24 pediatric patients with ependymomas/ependymoblastomas underwent surgery at our medical center, and 21 tumors were submitted for chromosome analysis. Three tumors failed to grow in culture and no analysis was possible, 10 tumors had apparently normal karyotypes, and 8 had abnormal karyotypes. Table 1 summarizes clinical data for 17 cases of karyotyped ependymomas and 1 ependymoblastoma. Age at diagnosis varied from less than 1 year to 15 years; the age of 12 of 18 patients
Discussion
Cytogenetic analyses of both pediatric and adult ependymomas have failed to identify any simple diagnostic marker or consistent pattern of cytogenetic abnormalities, with the possible exception of monosomy 22 or structural abnormality of 22q. Table 4 summarizes results from 125 ependymomas and ependymoblastomas, including 107 published cases of banded cytogenetic analyses 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
Acknowledgements
We are indebted to Dr. Ruthann Blough for FISH analysis of tumor number 1, and to Mrs. Denise Bellman for excellent assistance with the manuscript.
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