Extraventricular anaplastic ependymoma with metastasis to scalp and neck

We report a case of anaplastic ependymoma with extracranial metastases in a 22-year-old female. The patient originally presented with headaches and dysarthria. Neuroimaging revealed a large solid and cystic right fronto-temporal lesion. It was located completely extraventricularly and a glioblastoma was suspected based on the neuroimaging findings. A gross total resection was achieved. Histopathologic examination revealed an anaplastic ependymoma. The patient was treated with radiotherapy. Approximately 1 year after the initial surgery, the patient presented with metastatic disease to the scalp. At 2 years, an intraparotid metastasis was detected. Subsequent neck dissection revealed positive lymph nodes at several levels. It was followed by radiotherapy to the neck. 5 years after the initial surgery, the patient has residual metastatic disease. The case is discussed and the literature on extraventricular ependymal neoplasms is reviewed.     

Ependymoblastoma. A reappraisal of a rare embryonal tumor

This article reviews the clinicopathologic features of 12 ependymoblastomas, including those of 7 previously unreported cases. The histologic characteristics included a high density of small to medium-sized neuroepithelial cells with a uniform cytologic appearance, frequent mitotic figures, and numerous diagnostic ependymal rosettes and tubules. Differentiation was restricted to glial precursor cells and to cells with the differentiating features of ependymal cells. Cytogenetically, the tumor cells with the differentiating hallmarks of ependymal cells but which have retained their mitotic activity were considered to be ependymoblasts. Many of the rosettes in the tumors were of the ependymoblastic type, but ependymal rosettes were also present. The absence of pleomorphism, giant cells, multinucleation and pseudopalisades, and the scanty proliferation of vascular endothelial cells are additional features that delineate this tumor from an anaplastic (malignant) ependymoma. The median age of the patients was 2 years. After surgical treatment the median survival time was 12 months. Because of the frequency of leptomeningeal involvement, whole neuraxis radiation should be considered.     

Ependymoma with cartilaginous metaplasia might have more aggressive behavior: a case report and literature review

Ependymoma with cartilaginous metaplasia with or without bone formation is exceedingly rare. Only eight cases have been reported in the literature. We report a case of ependymoma with cartilaginous and osseous metaplasia in a 5-year-old boy. Microscopically, the tumor was composed of neoplastic ependymal tissue and mature cartilage and bone. Immunohistochemically, glial fibrillary acidic protein and epithelial membrane antigen were positive for ependymoma cells but negative for cartilage and bone. Recurrence occurred after 15-month follow-up. The patient deteriorated rapidly and died after 1 month. Reviewing 8 reported cases and our latest case, we found that 3 cases of ependymoma with cartilaginous metaplasia were treated with radiotherapy. Six cases had recurrence from 6 months to 8 years and 2 cases died on the day of operation. These findings suggest that ependymoma with cartilaginous metaplasia might have more aggressive clinical behavior.     

Glioblastoma multiforme with epithelial appearance: a case report

A case of glioblastoma multiforme with epithelial appearance, which was difficult to diagnose at first operation, is described. Microscopy revealed small, darkly staining anaplastic cells which were densely packed. In some areas, these cells were arranged in a tubular, gland-like pattern mimicking a poorly differentiated epithelial neoplasm. Immunostaining of glial fibrirally acidic protein (GFAP) was negative in the densely compact anaplastic areas and within the epithelial patterns, except for a small number of cells in one area. Further pathological study at the second and third operations indicated that the tumor consisted of neoplastic astrocytes and had characteristic features of glioblastoma multiforme, including necrosis, pseudopalisading, and endothelial proliferation. Many of the tumor cells were GFAP-positive. This rare case of glioblastoma multiforme was compared with cases reported in the literature.     

Tanycytic ependymoma of the spinal cord with anaplastic cytological features

In a 43-year-old man, an intramedullary spinal cord tumor spreading from the level of the T2 to T5 vertebrae was subtotally resected. The tumor predominantly consisted of a fascicular proliferation of spindle cells having bland nuclei and bipolar, long cytoplasmic processes, and a few perivascular pseudo-rosettes were found. Although there were no true ependymal rosettes, intracytoplasmic dot-like immunoreactivity for epithelial membrane antigen (EMA) was found in a few cells. In some areas, a dense and diffuse proliferation of anaplastic, short-spindled cells having hyperchromatic nuclei and scant cytoplasm was noted, and the Ki-67 labeling index was remarkably higher (18.2%) in these areas. Neither microvascular proliferation nor necrosis was observed. In the boundary region, these two areas showed gradual transition from one to the other. The patient has remained free from recurrence for 10 months postoperatively. This is the first documentation of tanycytic ependymoma in which tumor cells showed anaplastic cytological features.     

Tumor imprint cytology of ovarian ependymoma. A case report.

BACKGROUND: Ependymoma is a tumor that usually develops in the central nervous system and is extremely rare in the ovary. The first case of ovarian ependymoma was reported by Kleinman et al. (Kleinman GM, Young RH, Scully RE. Ependymoma of the ovary: report of three cases. Hum Pathol 1984;15:632-8.) in 1984, and only eight cases have been reported since then. Criteria for the histopathologic diagnosis of ependymoma are already established, but there has been no investigation of the cytologic diagnosis of ovarian ependymoma. METHODS: An imprint cytologic specimen was obtained from a recurrent ovarian ependymoma. The imprint cytologic features were compared with the findings of histologic examination, immunostaining, and electron microscopy. RESULTS: Imprint cytology revealed clusters of small cells with tapering cytoplasmic processes and a round nucleus. On the basis of these features, a neurogenic tumor could be included in the differential diagnosis. Furthermore, many rosette-like collections of cells that were suggestive of ependymal rosettes or perivascular pseudorosettes, characteristic of ependymoma, were found. The presence of ependymal rosettes and perivascular pseudorosettes also were confirmed by the histopathologic examination. Together with positive immunostaining for glial fibrillary acidic protein, this led to the diagnosis of ependymoma, which also was supported by the electron microscopic findings. CONCLUSIONS: Careful observation of the imprint cytologic specimen of an ovarian ependymoma should reveal numerous rosette-like collections of cells that were suggestive of ependymal rosettes or perivascular pseudorosettes. In addition, if we remember that ependymoma can develop in the ovary and find cells with tapering processes that suggest a neurogenic tumor, it may be possible to detect histologic features characteristic of ependymoma by the imprint cytology. To our knowledge, this is the first report on the imprint cytologic diagnosis of ependymoma originating in the ovary.     

Rhabdoid glioblastoma in a child: case report and literature review

Rhabdoid glioblastoma is a rare type of glioblastoma characterized by cells resembling rhabdomyoblasts. Several reports have identified its aggressive clinical course and the pathological differences from other primary brain tumors. We report a case of rhabdoid glioblastoma in a 12-year-old boy who presented with headache and harbored a 70-mm solid tumor in the left temporal lobe. The tumor was surgically excised, but early tumor recurrence and leptomeningeal spread developed, and the patient died of the disease 4.9 months after surgery. Histologically, the tumor contained two distinct patterns of glioblastoma and rhabdoid cells with necrosis and hemorrhage. Immunohistochemical analysis revealed that both cells were positive for glial fibrillary acid protein, vimentin, and INI1, which is consistent with the reported diagnosis of rhabdoid glioblastoma. Genetic studies confirmed no loss of the INI1 gene and identified hemizygous deletion of the CDKN2A gene. We review reported cases of rhabdoid glioblastoma and summarize the clinical, radiological, and histological features.     

Tandem high-dose chemotherapy and autologous stem cell transplantation for anaplastic ependymoma in children younger than 3 years of age

The present study evaluates the feasibility and effectiveness of tandem high-dose chemotherapy and autologous stem cell transplantation (HDCT/autoSCT) in very young children with anaplastic ependymoma. We aimed both to improve survival and to avoid unacceptable late adverse effects of radiation therapy (RT) by avoiding or deferring RT until 3 years of age. Five consecutive patients younger than 3 years of age with anaplastic ependymoma were enrolled from April 2006 to November 2008. Tandem HDCT/autoSCT was given following six cycles of induction chemotherapy. RT was either not given or deferred until 3 years of age if the patient was in complete response after tandem HDCT/autoSCT. Median age at diagnosis was 16 (range 12–28) months. Four patients had significant residual tumor (>1.5 cm²) after initial surgery, and three had leptomeningeal seeding. Toxicities during induction chemotherapy and tandem HDCT/autoSCT were manageable. No tumor progressed during induction chemotherapy and tandem HDCT/autoSCT, and RT was thus avoided or deferred until 3 years of age in all patients. All patients are alive at median follow-up of 45 (range 31–62) months from diagnosis, although tumor progressed in one patient. No significant endocrine dysfunction occurred except for hypothyroidism in one patient. Cognitive function was also acceptable in all patients but one who had significant neurologic injury during surgery. Our results indicate that treatment with tandem HDCT/autoSCT is feasible in very young children with anaplastic ependymoma and may improve the survival of patients with acceptable long-term toxicity.     

Supratentorial extraventricular anaplastic ependymoma in an adult with repeated intratumoral hemorrhage

We report the case of a 61-year-old man with supratentorial extraventricular anaplastic ependymoma who presented with repeated intratumoral hemorrhage. The patient was admitted with headache. Computed tomography and magnetic resonance imaging showed an enhancing mass with intratumoral hemorrhage in the right temporal lobe. Gross total resection was performed. The tumor was well demarcated from the brain tissue, and showed no continuity with the ventricular system. Histopathological examination revealed the features of anaplastic ependymoma. Therefore, additional radiation therapy and adjuvant chemotherapy were administered. Ten months later, the tumor recurred with hemorrhage in the spinal canal. This case showed rapid malignant progression and repeated intratumoral hemorrhage within a short period of time, both of which are characteristics of anaplastic ependymomas. Close observation of the central nervous system and adjuvant radiotherapy are mandatory, even if the ependymoma presents with repeated intratumoral hemorrhage.     

A case of angioglioma composed of astrocytoma with a papillary growth pattern: Immunohistochemical and ultrastructural studies

We report a case of a large cystic astrocytoma associated with arteriovenous malformation in the right cerebral hemisphere of a 16-year-old boy. Neuroimaging showed large abnormal vessels with flow voids and arteriovenous shunt around the cystic lesion. Histologically, the cyst wall was formed by abnormal vasculature and clusters of glial cells forming a papillary growth pattern. The abnormal vasculature consisted of dilated vein-like vessels and medium-sized arteries with incomplete media, and was diagnosed as an arteriovenous malformation. Immunohisto-chemically, glial fibrillary acidic protein (GFAP) decorated both the perikaryon and the processes of the glial tumor cells. They were negative for epithelial membrane antigen (EMA), cytokeratin, and S-100 protein. Ultrastructurally, the tumor cells were rich in intermediate filaments, and neither cilia, microvilli, nor ependymal rosettes were verified. Based on these morphological features and the low MIB-1 labeling index of 0.8%, the glial tumor was diagnosed as astrocytoma, Grade II, according to the World Health Organization (WHO) tumor classification. An association of glioma with various types of vascular anomalies has been designated as angioglioma. A unique feature of the present case, however, is a papillary growth pattern, which is not listed in the current WHO classification of brain tumors. The recognition of the occurrence of such cases would be important in differential diagnosis of papillary ependymoma and choroid plexus papilloma.     

Cervical cord ependymoma with numerous microrosettes

“Microrosette ependymoma,” which is ependymoma with numerous microrosettes throughout the tumor, has rarely been reported. We describe an autopsy case of cervical cord ependymoma with two unusual features: the presence of numerous microrosettes and the formation of trabecular architecture. The tumor originated in the C2 segment of a man aged 23 years and gradually expanded over the following 15 years and 10 months until the entire cervical cord was involved. Beside the low grade of malignancy, the tumor cells exhibited a strong tendency to form microrosettes and trabecular architecture, which formed many perivascular pseudorosettes. The microrosettes mostly consisted of only two or a few more cells, in the absence of large rosettes. Thus the constituent cells were those forming perivascular pseudorosettes. Electron microscopy and immunohistochemistry characterized the ependymal properties of the microrosettes, whose lumina frequently contained fibril bundles similar to those of the Reissner's fiber fibrils, in addition to cilia and microvilli. The pathogenesis of the occurrence of numerous microrosettes is unknown; however, a defect in the mechanism of regulation of rosette formation and enlargement is the most likely explanation.     

Persistent roles of signal transduction of platelet-derived growth factor B in genesis,growth, and anaplastic transformation of gliomas in an in-vivo serial transplantation model

We previously reported that retrovirally transduced platelet-derived growth factor-B (PDGFB) in glial progenitors of the rat cerebral white matter, subventricular zone, or brain stem induced malignant brain tumors closely resembling human glioblastoma (GBM). While human GBMs may progress over the period of several months to a few years, prospective, long-term in-vivo observation of histological changes of the tumor tissues is not feasible in these models, because the animals undergo rapid tumor progression and mortality within approximately 1 month. We thus performed successive, long-term in-vivo transplantation of the PDGFB-induced tumor cells into the rat cerebrum. Primary retroviral transduction of PDGFB in the glial progenitors of the rat basal ganglia induced malignant glioma resembling human GBM or anaplastic oligodendroglioma (AOL) consisting of relatively monomorphous tumor cells expressing markers for the oligodendrocyte lineage. In the course of long-term successive transplantation, tumor cells presented pleomorphism as well as focal GFAP expression. This suggests that secondary chromosomal aberration and dysregulation of gene expression following accelerated cell cycle by PDGFB stimulation would induce morphological and immunophenotypic changes in tumor cells. Furthermore, while the primary tumors contained only a minor fraction of proviral GFP-expressing or hemagglutinin-expressing cells, most tumor cells came to express these proviral genes in the course of serial transplantation suggesting a persistent role of PDGFB-expressing cells in maintenance and growth of the tumors. This model would be useful for investigation of the long-term effects of PDGFB stimulation in glioma tissues on anaplastic evolution.     

A case of an anaplastic ependymoma with gliosarcomatous components

A 29-year-old woman presented with a severe headache. Computed tomography revealed a large cystic lesion with a mural nodule-like mass homogeneously enhanced with contrast medium in the right cerebellum. The tumor was removed, and pathological studies revealed a cerebellar astrocytoma corresponding to World Health Organization grade II. When she was 35 years old, or 6 years after the surgery, magnetic resonance imaging revealed a recurrence of the tumor in the right cerebellum, and subtotal removal of the recurrent tumor was performed. Pathological studies revealed a mixed glioblastoma multiforme and anaplastic ependymoma. Chemotherapy (Paraplatin and VePeside-S) and focal radiation therapy at 60 Gy were administered following surgery. Thereafter, at 39 years of age, or 4 years after radiation therapy, magnetic resonance imaging again revealed a recurrence of the tumor, which was heterogeneously enhanced with gadoliniumdiethylenetriamine pentaacetic acid in the right cerebellum. Subtotal removal of the tumor was performed; pathological studies revealed an anaplastic ependymoma with sarcomatous components. Immunohistochemical findings showed some parts of the sarcomatous components to stain positively for glial fibrillary acidic protein and, as a result, these sarcomatous components were diagnosed to be gliosarcoma. This case was presented at the 26th annual meeting of the Japan Society of Brain Tumor Pathology, 2008.     

Cerebrospinal fluid cytology in patients with ependymoma

BACKGROUND.

Ependymoma cells are known to occasionally exfoliate into cerebrospinal fluid (CSF). However, the frequency of CSF involvement in patients with ependymoma is unclear, and to the authors' knowledge the cytomorphologic features of the tumor cells have not been described in detail to date. In this study, the CSF findings in patients with ependymal neoplasms are summarized and the cytomorphologic features of ependymoma, including its variants, are illustrated.

METHODS.

A search of the pathology databases of 2 medical centers was performed to identify all patients with a histologic diagnosis of ependymoma in whom CSF samples were examined. Slides from CSF samples originally reported as atypical, suspicious, or positive were reviewed and the cytomorphologic features assessed. Follow‐up included a review of the medical records and histologic correlation.

RESULTS.

In all, 177 patients with a diagnosis of ependymoma were identified. Of these, 48 had a total of 94 cytologic preparations of CSF. Positive, suspicious, atypical, negative, and nondiagnostic results were noted in 6.4%, 5.3%, 4.3%, 79.7%, and 4.3%, respectively, of the specimens. The detection rate of tumor cells in CSF was 6.7% in 15 adults and 21.2% in 33 children, with an overall rate of 16.7%. Of the 8 patients with positive and/or suspicious diagnoses, 5 ependymomas exhibited anaplastic features and 1 tumor was a myxopapillary ependymoma. The positive samples were usually hypercellular, with cohesive epithelioid cells; long cytoplasmic processes resembling bipolar tanycytes were observed in the tanycytic variant of ependymoma.

CONCLUSIONS.

Exfoliated cells from ependymomas are recognizable in CSF samples, especially in patients with myxopapillary tumors and tumors with anaplastic features. Cancer (Cancer Cytopathol) 2008. © 2008 American Cancer Society.     

A case of cervicomedullary junction tanycytic ependymoma associated with marked cyst formation

Tanycytic ependymomas are a subtype of ependymomas that were formally recognized as a new pathological entity in the latest World Health Organization (WHO) classification of 2000. They occur mostly in the spinal cord. Only a few reports have analyzed the proliferative potentials of these tumors; however, it has been reported that the MIB-1 labeling index of tanycytic ependymoma is lower than that of other subtypes of WHO grade II ependymomas. We report a rare case of cervicomedullary junction tanycytic ependymoma associated with marked cyst formation. A 62-year-old man had a history of progressive gait disturbance, diplopia, and swallowing disturbance over a one-month period prior to admission. Magnetic resonance imaging (MRI) showed a cystic mass with a mural nodule at the cervicomedullary junction with Gd-DTPA enhancement. Cyst-subarachnoid shunt was performed using a far lateral approach. After 6 years, however, the man was readmitted to the hospital because of reaccumulation of the cyst. Partial removal of a mural nodule and a cyst-subarachnoid shunt were performed simultaneously by a midline suboccipital approach. The pathological diagnosis was tanycytic ependymoma. Postoperatively, the patient recovered well and was discharged from the hospital without further treatment. Most of the tumor cells had small, round nuclei; pleomorphism was minimal. The cytoplasm was dilated. The tumor cells were positive for EMA and s-100, and negative for CD-34. GFAP was not determined due to difficulty caused by background glial processes. The MIB-1 labeling index was less than 1%. Ultrastructurally, the tumor cells had ependymal cell features, such as desmosomes and microvilli. Based on these findings, the pathological diagnosis was tanycytic ependymoma.     

A case of anaplastic clear-cell ependymoma presenting with high erythropoietin concentration and 1p/19q deletions

We describe a 19-year-old woman with onset of epileptic seizure, and a small mural nodule and multicystic lesions with severe brain edema located in the right frontal lobe. At surgery, the tumor and a clear margin was removed, and symptoms improved postoperatively. Extended local radiotherapy (60 Gy) was performed. Histopathological examination revealed oligodendroglioma-like tumor cells with a perinuclear halo. The tumor cells extended processes toward CD34-positive proliferating vessels, which resemble a basement membrane. These proliferating vessels formed a tumor membrane so that there was a clear margin between the tumor and brain tissue. Tumor cells were positive for epithelial membrane antigen in a dot-like pattern. MIB-1 staining index was 50.6%. Electron microscopy showed cilia and zipper-like junctions, and anaplastic clear-cell ependymoma grade III was diagnosed. A characteristic of the case was formation of a tumor membrane by proliferating tumor blood vessels. Fluorescence in situ hybridization showed 1p/19q deletions, and the concentration of erythropoietin in the cyst fluid was abnormally high, at 1,859.4 mIU/ml. Erythropoietin and erythropoietin receptors were verified with immunohistochemical staining.     

A case of tanycytic ependymoma arising from the cerebral hemisphere

We report a rare case of tanycytic ependymoma arising from the cerebral hemisphere. A 59-year-old man was admitted to our hospital because of the incidental detection by MRI of a tumor lesion in the right temporooccipital paratrigonal region. The mass showed low-to iso-intensity on T₁-weighted images and high intensity on T₂/proton-weighted images. Partial resection was performed using a transsulcal approach to avoid compromising the visual field. Most of the tumor cells showed elongated spindle shapes arranged in dense fascicles. A few true ependymal rosettes and perivascular pseudorosettes were visible. The tumor cells were positive for GFAP, S-100, and vimentin, but negative for synaptophysin, EMA, and keratin. The MIB-1 labeling index was approximately 1%. Ultrastructurally, the tumor cells had ependymal cell features, such as microvilli and cilia. From these findings, a pathological diagnosis of tanycytic ependymoma was made.     

Anaplastic myxopapillary ependymoma: A case report and review of literature

BACKGROUNDMyxopapillary ependymoma (MPE) is a pathological grade I tumor that arises in the filum terminale. MPE with anaplastic features is extremely rare, and only 5 cases have shown malignancy at the time of recurrence.CASE SUMMARYThe patient (a 46-year-old woman) had undergone a MPE operation 30 years ago. After subtotal resection of the tumor located in L4-S1, it had a solid component that extended to the adjacent subcutaneous region. Histologically, the tumor consisted of a typical MPE with anaplastic features. The anaplastic areas of the tumor showed hypercellularity, a rapid mitotic rate, vascular proliferation, and connective tissue proliferation. Pleomorphic cells and atypical mitotic figures were occasionally observed. The MIB-1 index in this area was 12.3%. The immunohistochemical study showed immunoreactivity for vimentin, glial fibrillary acidic protein and S100. The morphological pattern and immunohistochemical profile were consistent with anaplastic MPE. The patient tolerated surgery well without new neurological deficits. She underwent local irradiation for the residual tumor and rehabilitation.CONCLUSIONAlthough extremely rare, anaplastic MPE occurs in both pediatric and adult patients, similar to other ependymomas. At a minimum, close monitoring is recommended, given concerns about aggressive biological potential. In the future, further study is needed to determine the WHO classification criteria and genetic indicators of tumor progression. The possibility of malignant transformation of MPE should be taken into account, and patients with MPE should be treated with care and follow-up.     

Elevated expression of macrophage migration inhibitory factor correlates with tumor recurrence and poor prognosis of patients with gliomas

Macrophage migration inhibitory factor (MIF) plays a critical role in tumorigenesis. We aim to examine the association of MIF with tumor recurrence and survival of gliomas, and to determine whether MIF is a valuable prognostic predictor for glioma patients. The expression of MIF and interleukin 8 (IL-8) was evaluated in 36 high-grade gliomas (20 glioblastoma multiforme, 13 anaplastic astrocytoma, and 3 anaplastic oligoastrocytoma) and 32 low-grade gliomas (18 fibrillary astrocytoma, 5 pilocytic astrocytoma, 5 oligodendroglioma, 3 ependymoma and 1 pleomorphic xanthoastrocytoma) by immunostaining. Intratumoral microvessel density (IMD) of tumors in relation to immunostainings and clinicopathological factors were analyzed statistically as well as the follow-up data of patients. High expression of both MIF (58.8%) and IL-8 (52.9%) was significantly associated with high-grade gliomas and increased microvessels in tumors, but only high expression of MIF was closely related to tumor recurrence (P = 0.001). High expression of IL-8 exhibited a close correlation with high expression of MIF in tumors (P = 0.001). Histological grading, high expression of MIF and IL-8 correlated with patients’ overall survival in univariate analysis. However, only histological grading and MIF expression exhibited a relationship with survival of patients as independent prognostic factors of glioma by multivariate analysis; the hazard ratios were 28.012 (P = 0.001) and 11.782 (P = 0.001), respectively. Elevated production of MIF in glioma tumor cells may contribute to tumor recurrence and a worse prognosis. MIF may serve as an independent predictive factor for prognosis of glioma patients.     

Radiosurgery in the management of pediatric brain tumors.

OBJECTIVE: To describe the outcome of pediatric brain tumor patients following stereotactic radiosurgery (SRS), and factors associated with progression-free survival. METHODS: We reviewed the outcome of 90 children treated with SRS for recurrent (n = 62) or residual (n = 28) brain tumors over a 10-year period. Median follow-up from SRS was 24 months for all patients and 55.5 months for the 34 patients currently alive. RESULTS: The median progression-free survival (PFS) for all patients was 13 months. Median PFS according to tumor histology was medulloblastoma = 11 months, ependymoma = 8.5 months, glioblastoma and anaplastic astrocytoma = 12 months. Median PFS in patients treated to a single lesion was 15.4 months. No patient undergoing SRS to more than 1 lesion survived disease free beyond 2 years. After adjusting for histology and other clinical factors, SRS for tumor recurrence (RR = 2.49) and the presence of > 1 lesion (RR = 2.3) were associated with a significantly increased rate of progression (p < 0.05). Three-year actuarial local control (LC) was as follows: medulloblastoma = 57%, ependymoma = 29%, anaplastic astrocytoma/glioblastoma = 60%, other histologies = 56%. Nineteen patients with radionecrosis and progressive neurologic symptoms underwent reoperation after an interval of 0.6-62 months following SRS. Pathology revealed necrosis with no evidence of tumor in 9 of these cases. CONCLUSION: SRS can be given safely to selected children with brain tumors. SRS appears to reduce the proportion of first failures occurring locally and is associated with better outcome when given as a part of initial management. Some patients with unresectable relapsed disease can be salvaged with SRS. SRS to multiple lesions does not appear to be curative. Serious neurologic symptoms requiring reoperation is infrequently caused by radionecrosis alone.