Korgun Koral

Imaging Characteristics of Atypical Teratoid–Rhabdoid Tumor in Children Compared with Medulloblastoma

OBJECTIVE The purpose of our study was to compare the imaging characteristics of atypical teratoid-rhabdoid tumor with medulloblastoma and seek distinguishing features that can aid in preoperative diagnosis. MATERIALS AND METHODS Preoperative MRI examinations of 55 patients (36 medulloblastomas and 19 atypical teratoid-rhabdoid tumors) were analyzed retrospectively. Imaging characteristics of atypical teratoid-rhabdoid tumor and medulloblastoma were assessed with conventional MRI and CT. Diffusion-weighted imaging (DWI) was available in 27 patients (19 medulloblastomas and eight atypical teratoid-rhabdoid tumors). Apparent diffusion coefficient (ADC) values were calculated for 14 medulloblastomas and six atypical teratoid-rhabdoid tumors. RESULTS Both atypical teratoid-rhabdoid tumors in general and infratentorial atypical teratoid-rhabdoid tumors presented at a younger age than medulloblastomas. Eleven of 19 atypical teratoid-rhabdoid tumors were infratentorial. Cerebellopontine angle (CPA) involvement was more frequent (8/11, 72.7%) in atypical teratoid-rhabdoid tumor than in medulloblastoma (4/36, 11.1%) (p < 0.001). Intratumoral hemorrhage was more common in atypical teratoid-rhabdoid tumor (9/19, 47.4%) than in medulloblastoma (2/36, 5.6%) (p < 0.0001). All atypical teratoid-rhabdoid tumors and all medulloblastomas for which DWI was available displayed increased signal intensity on DWI compared with normal brain parenchyma. The mean ADC values for tumor types were not significantly different. CONCLUSION Atypical teratoid-rhabdoid tumor presents at a younger age than medulloblastoma. Although atypical teratoid-rhabdoid tumor and medulloblastoma display similar imaging characteristics on conventional MRI, CPA involvement and intratumoral hemorrhage are more common in atypical teratoid-rhabdoid tumor. If a pediatric posterior fossa mass that displays restricted diffusion is involving the CPA, atypical teratoid-rhabdoid tumor is a more likely consideration than medulloblastoma.

Acute silent cerebral ischemia and infarction during acute anemia in children with and without sickle cell disease

We hypothesized that the silent cerebral infarcts (SCI), which affect up to 40% of children with sickle cell disease (SCD), could occur in the setting of acute anemic events. In a prospective observational study of children with and without SCD hospitalized for an illness associated with acute anemia, we identified acute silent cerebral ischemic events (ASCIE) in 4 (18.2%) of 22 with SCD and in 2 (6.7%) of 30 without SCD, using diffusion-weighted magnetic resonance imaging. Children with ASCIE had lower hemoglobin concentration than those without (median 3.1 vs 4.4 g/dL, P = .003). The unique temporal features of stroke on diffusion-weighted magnetic resonance imaging permit estimation of incidence rates for ASCIE of 421 (95% confidence interval, 155-920) per 100 patient-years during acute anemic events for all patients. For children with SCD, the estimated incidence was 663 (95% confidence interval, 182-1707) which is much higher than previously reported. Acute anemic events are common in children with SCD and prevalence could partially account for the high SCI. Some ASCIE (1 of 4 in our study) may be reversible. Alterations in management may be warranted for children with severe anemia to identify unrecognized ischemic brain injury that may have permanent neurocognitive sequelae.

Strengthening the Argument for Rapid Brain MR Imaging: Estimation of Reduction in Lifetime Attributable Risk of Developing Fatal Cancer in Children with Shunted Hydrocephalus by Instituting a Rapid Brain MR Imaging Protocol in Lieu of Head CT

BACKGROUND AND PURPOSE: Children with shunted hydrocephalus have been undergoing surveillance neuroimaging, generally in the form of head CT, for evaluation of ventricular size. As the life expectancy of these children has improved due to better shunt technology and medical care, risks related to the ionizing radiation incurred during multiple head CT examinations that they are expected to undergo throughout their lifetime have become a concern. The purpose of this study is to estimate the LAR of developing fatal cancer due to head CT for ventricular size assessment in children with shunted hydrocephalus and to assess the impact of instituting a rapid brain MR imaging protocol in reducing radiation exposure. MATERIALS AND METHODS: Retrospective review of medical records yielded 182 patients who underwent neuroimaging for assessment of ventricular size. Available neuroimaging studies (head CT and rapid brain MR) were counted and annual neuroimaging frequency was calculated. It was assumed that these patients undergo a similar number of neuroimaging studies annually through 20 years of age. A risk estimate was calculated based on the BEIR VII report and effective doses obtained using the International Commission on Radiologic Protection Report 103 organ weighting factors. RESULTS: The mean annual neuroimaging study frequency was 2.1. Based on the average age of 1.89 years, it was assumed neuroimaging surveillance commences in the second year of life. LAR was calculated assuming that a patient undergoes neuroimaging in the form of head CT at this frequency (2/year) through 20 years of age. Assuming 2 scans are performed per year and the low-dose head CT protocol is used, approximately 1 excess lifetime fatal cancer would be generated per 230 patients; with standard head CT, there would be 1 excess lifetime fatal cancer per 97 patients. CONCLUSIONS: Children with shunted hydrocephalus are at increased risk of developing fatal cancer if they are to undergo surveillance using head CT. Implementation of a rapid brain MR imaging protocol with no radiation detriment will reduce this risk.

Utility of Apparent Diffusion Coefficient Ratios in Distinguishing Common Pediatric Cerebellar Tumors

RATIONALE AND OBJECTIVES The aim of this study was to identify clinically useful tumor/normal brain apparent diffusion coefficient (ADC) ratios for distinguishing common pediatric cerebellar tumors. MATERIALS AND METHODS Review of medical records revealed 79 patients with cerebellar tumors who underwent preoperative magnetic resonance imaging, including diffusion-weighted imaging sequences, and surgery. There were 31 pilocytic astrocytomas, 27 medulloblastomas, 14 ependymomas, and seven atypical teratoid/rhabdoid tumors. ADC values were measured by placing regions of interest on the solid tumor and normal brain parenchyma by two reviewers. Tumor/normal brain ADC ratios were calculated. RESULTS Mean ADC values of the pilocytic astrocytomas were greater than those of ependymomas, whose mean ADC values were greater than those of medulloblastomas and atypical teratoid/rhabdoid tumors. Using a tumor/normal brain ADC ratio threshold of 1.70 to distinguish pilocytic astrocytomas from ependymomas, sensitivity of 92% and specificity of 79% were achieved. A tumor/normal brain ADC ratio threshold of 1.20 enabled the sorting of ependymomas from medulloblastomas with sensitivity of 93% and specificity of 88%. CONCLUSIONS Tumor/normal brain ADC ratios allow the distinguishing of common pediatric cerebellar tumors.

Common Pediatric Cerebellar Tumors: Correlation between Cell Densities and Apparent Diffusion Coefficient Metrics

PURPOSE To test whether there is correlation between cell densities and apparent diffusion coefficient (ADC) metrics of common pediatric cerebellar tumors. MATERIALS AND METHODS This study was reviewed for issues of patient safety and confidentiality and was approved by the Institutional Review Board of the University of Texas Southwestern Medical Center and was compliant with HIPAA. The need for informed consent was waived. Ninety-five patients who had preoperative magnetic resonance imaging and surgical pathologic findings available between January 2003 and June 2011 were included. There were 37 pilocytic astrocytomas, 34 medulloblastomas (23 classic, eight desmoplastic-nodular, two large cell, one anaplastic), 17 ependymomas (13 World Health Organization [WHO] grade II, four WHO grade III), and seven atypical teratoid rhabdoid tumors. ADCs of solid tumor components and normal cerebellum were measured. Tumor-to-normal brain ADC ratios (hereafter, ADC ratio) were calculated. The medulloblastomas and ependymomas were subcategorized according to the latest WHO classification, and tumor cellularity was calculated. Correlation was sought between cell densities and mean tumor ADCs, minimum tumor ADCs, and ADC ratio. RESULTS When all tumors were considered together, negative correlation was found between cellularity and mean tumor ADCs (ρ = -0.737, P < .05) and minimum tumor ADCs (ρ = -0.736, P < .05) of common pediatric cerebellar tumors. There was no correlation between cellularity and ADC ratio. Negative correlation was found between cellularity and minimum tumor ADC in atypical teratoid rhabdoid tumors (ρ = -0.786, P < .05). In atypical teratoid rhabdoid tumors, no correlation was found between cellularity and mean tumor ADC and ADC ratio. There was no correlation between the ADC metrics and cellularity of the pilocytic astrocytomas, medulloblastomas, and ependymomas. CONCLUSION Negative correlation was found between cellularity and ADC metrics of common pediatric cerebellar tumors. Although ADC metrics are useful in the preoperative diagnosis of common pediatric cerebellar tumors and this utility is generally attributed to differences in cellularity of tumors, tumor cellularity may not be the sole determinant of the differences in diffusivity.

Predictors of tumor progression among children with gangliogliomas. Clinical article.

OBJECT Few reports describe the outcome and prognostic factors for children with gangliogliomas. The objective of this report was to describe the progression-free survival (PFS) for children with low-grade gangliogliomas and identify risk factors for tumor progression. METHODS A retrospective study was performed in children with low-grade gangliogliomas who were evaluated and treated in the neuro-oncology department between 1986 and 2006 to determine risk factors for subsequent tumor progression. RESULTS A total of 38 children with newly diagnosed gangliogliomas were included in this report. Thirty-four children were treated with surgery alone, 3 with subtotal resection and radiation therapy, and 1 with subtotal resection and chemotherapy. The follow-up ranged from 4 months to 15.8 years (mean 5.7+/-4.2 years [+/-SD]). Seven children have experienced tumor progression, and 1 child died after his tumor subsequently underwent malignant transformation. The 5-year PFS was calculated to be 81.2% using Kaplan-Meier survival analysis. Initial presentation with seizures (p=0.004), tumor location in the cerebral hemisphere (p=0.020), and complete tumor resection (p=0.035) were associated with prolonged PFS. Further analysis of the above significant variables by a Cox regression model identified initial presentation with seizures as being associated with prolonged PFS (p=0.028). CONCLUSIONS The PFS and overall survival of children with gangliogliomas are good. Tumors located in the cerebral hemispheres, the achievement of total resection, and seizures at presentation were associated with prolonged PFS. Cox regression analysis identified presenting symptoms including seizures as significant predictive factors of PFS. Prospective studies with larger numbers of children are needed to define the significant factors of tumor progression.

Pleomorphic Xanthoastrocytoma of Childhood: MR Imaging and Diffusion MR Imaging Features

BACKGROUND AND PURPOSE: Pleomorphic xanthoastrocytomas are rare astrocytic neoplasms of childhood and young adulthood. The purpose of this retrospective review was to evaluate MR imaging features of pediatric pleomorphic xanthoastrocytomas with an emphasis on diffusion MR imaging. MATERIALS AND METHODS: Review of the neuro-oncology data base revealed 11 pediatric patients (range, 4.7–16.1 years) with pleomorphic xanthoastroacytomas with 9 of these patients having preoperative MR imaging available. Six patients had preoperative diffusion MR imaging. Demographics, histopathology slides, conventional imaging characteristics (location, cystic component, hemorrhage, enhancement, vasogenic edema, inner table scalloping), and ADC metrics (mean tumor ADC and tumor to normal brain ADC ratio) were evaluated. RESULTS: Three pleomorphic xanthoastrocytomas had anaplastic features. Ten tumors were supratentorial. Two-thirds (6 of 9) of all tumors were either predominantly cystic or had cystic components, and three-fourths (6 of 8) of the supratentorial tumors had associated inner table scalloping. Seven of the 9 tumors had marked vasogenic edema (>10 mm). Mean tumoral ADC (n = 7) was 912 ± 219 × 10−6 mm2/s (min–max: 617–1189). The tumor to normal brain ADC ratio was 1.14 ± 0.26 (min–max: 0.75–1.47). CONCLUSIONS: Pleomorphic xanthoastrocytoma should be entertained in the differential diagnosis of peripheral supratentorial tumors that appear during childhood. Cysts, inner table scalloping, and marked vasogenic edema are relatively frequent features. Relatively low ADC values and ADC ratios are not uncommon in pleomorphic xanthoastrocytoma.

Juvenile xanthogranulomas of the nervous system: A report of two cases and review of the literature.

Juvenile xanthogranulomas (JXG) are uncommon non‐Langerhans cell histiocytic proliferations which arise most often in children. While most cases present as solitary cutaneous lesions, occasional cases involve extracutaneous sites. Rare examples of JXGs have been reported involving all levels of the neuroaxis. We present two cases of JXGs involving the nervous system, and review the literature. The first patient was a 14‐year‐old female with headaches and a mass involving the left trigeminal nerve; pathologic examination showed a JXG. At 11 months follow‐up, after administration of systemic chemotherapy, the patient remained stable with residual tumor. The second patient was a 15‐year‐old female with leg weakness and numbness, who underwent complete surgical resection of a dural JXG. At eight months follow‐up, she showed no evidence of tumor, and was able to walk without difficulty. Review of the literature revealed 38 previously published reports of JXGs involving the nervous system. The CNS was involved in the majority (75%) of cases. The clinical characteristics of JXGs arising in the CNS varied significantly from cases in the peripheral nervous system (PNS); CNS tumors occurred in younger patients, more often males, and were more likely to be associated with concurrent cutaneous and extra‐nervous systemic lesions. The clinical outcomes were similar for CNS and PNS lesions, with the caveat that all three lethal JXGs occurred in the CNS. The clinical and radiologic presentation of JXGs is nonspecific, thus necessitating biopsy and pathologic examination to arrive at the diagnosis. The pathologic differential diagnosis includes a heterogeneous group of histiocytic proliferations; immunostaining for histiocytic markers CD68, factor XIIIa, and Fascin, and the absence of Birbeck granules and CD1a immunoexpression suggests the diagnosis of JXG. In many cases, total surgical resection is curative. However, some cases will require additional chemotherapy and/or radiotherapy.

Optic nerve and chiasm enlargement in a case of infantile Krabbe disease: quantitative comparison with 26 age-matched controls

Hypertrophy of the optic nerves and optic chiasm is described in a 5-month-old boy with infantile Krabbe disease. Optic nerve and optic chiasm hypertrophy is a rarely described feature of Krabbe disease. The areas of the prechiasmatic optic nerves and optic chiasm were measured and compared with those of 26 age-matched controls. The areas of the prechiasmatic optic nerves and optic chiasm were 132% and 53% greater than normal, respectively.

Angiocentric glioma in a 4-year-old boy: imaging characteristics and review of the literature

An angiocentric glioma of the right temporal lobe is presented in a 4-year-old male. Imaging characteristics of this newly codified glial neoplasm are discussed with a review of the literature.