Posterior fossa tumor in children

Primary brain tumors are the most common solid neoplasms of childhood, representing 20% of all pediatric tumors. The best current estimates place the incidence between 2.76 and 4.28/100,000 children per year. Compared with brain tumors in adults, a much higher percentage of pediatric brain tumors arise in the posterior fossa. Infratentorial tumors comprise as many as two thirds of all pediatric brain tumors in some large series. Tumor types that most often occur in the posterior fossa include medulloblastoma, ependymoma, cerebellar astrocytoma and brainstem glioma. All pediatric cases of posterior fossa tumor that were considered for surgery from 1981 to 2011 were selected and the demographic data including age, gender and tumor characteristics along with the location and pathological diagnosis were recorded. The surgical outcomes were assessed according to pathological diagnosis. Our series consisted of 84 patients [52 males, 32 females]. Cerebellar symptoms were the most common cause of presentation [80.9%] followed by headache [73.8%] and vomiting [38.1%]. The most common histology was medulloblastoma [42.8%] followed by cerebellar astrocytoma [28.6%], ependymoma [14.3%], brainstem glioma [7.2%] and miscellaneous pathologies [e.g., dermoid, and tuberculoma] [7.2%]. The diagnosis of brain tumors in the general pediatric population remains challenging. Most symptomatic children require several visits to a physician before the correct diagnosis is made. These patients are often misdiagnosed for gastrointestinal disorders. Greater understanding of the clinical presentation of these tumors and judicious use of modern neuroimaging techniques should lead to more efficacious therapies

Cisto epidermoide da fossa posterior: relato de caso / Epidermoid cyst of the posterior fossa: a case report

Epidermoid cysts of the central nervous system are uncommon conditions, which are frequently located in the cerebellopontine angle and around the pons. They are covered with keratinized squamous epithelium and keratin lamella, which give its contents a soft, white-pearly appearance. Epidermoid cysts are mostly originated from malformations, presumably associated with surface elements of the nervous system ectoderm during the closure of the neural groove or formation of secondary cerebral vesicles. The authors describe a case of epidermoid cyst in the posterior fossa causing hydrocephalus and review morphologic and diagnostic criteria of this lesion.

Os cistos epidermoides do sistema nervoso central (SNC) são condições incomuns, estando localizados mais frequentemente no ângulo pontocerebelar e ao redor da ponte. Eles são revestidos por epitélio escamoso queratinizado e lamelas de queratina, tornando seu conteúdo branco-perolado e pastoso. Os cistos epidermoides são, na maioria das vezes, originados de malformações, possivelmente associados ao entremeio de elementos superficiais do ectoderma do SNC durante o fechamento da placa neural, ou formação das vesículas cerebrais secundárias. Os autores descrevem um caso de cisto epidermoide da fossa posterior determinando hidrocefalia e revisam critérios morfológicos e diagnósticos dessa lesão.

Multicentric astrocytoma presenting with supra- and infratentorial involvement: a case report

This report describes the case of a 56 year-old man with a history of diplopia. His brain imaging showed multiple lesions with a metastatic appearance, however all investigations to determine the primary source of malignancy were negative. The patient underwent a brain biopsy, which was positive for anaplastic astrocytoma, a rare tumor that should be considered in the differential diagnosis of secondary brain tumors

Meduloblastoma: correlação entre ressonância magnética convencional, difusão e espectroscopia de prótons / Medulloblastoma: correlation among findings of conventional magnetic resonance imaging, diffusion-weighted imaging and proton magnetic resonance spectroscopy", "_i": "en

OBJETIVO: Correlacionar os achados de ressonância magnética convencional, difusão e espectroscopia de prótons nos meduloblastomas, e compará-los aos dados da literatura. MATERIAIS E MÉTODOS: Análise retrospectivade exames de ressonância magnética pré-operatórios de nove pacientes na faixa pediátrica com diagnóstico histológico de meduloblastoma (oito desmoplásicos e um de células gigantes). Foram considerados dados demográficos e características do tumor como localização, característica morfológica, intensidade de sinal, realce, disseminação e achados na difusão e espectroscopia. RESULTADOS: Na maioria dos casos os tumores apresentaram epicentro no vermis cerebelar (77,8%), sendo predominantemente sólido (88,9%), com hipossinal nas seqüências ponderadas em T1 e iso/hipersinal nas seqüências ponderadas em T2 e FLAIR, realce heterogêneo (100%), sinais de disseminação/extensão tumoral (77,8%) e restrição à movimentação das moléculas de água (100%). A espectroscopia de prótons pela técnica STEAM (n = 6) demonstrou redução da relação Naa/Cr (83,3%) e aumento de Co/Cr (100%) e mI/Cr (66,7%), e pela técnica PRESS (n = 7) evidenciou pico de lactato (57,1%). CONCLUSÃO: O conjunto dos achados macroscópicosobtidos pela ressonância magnética, somado às características bioquímicas dos meduloblastomas, têm sido úteis na tentativa de diferenciação entre os principais tumores da fossa posterior.

OBJECTIVE: To correlate imaging findings of medulloblastomas at conventional magnetic resonance imaging, diffusion-weighted imaging and proton magnetic resonance spectroscopy, comparing them with data in the literature. MATERIALS AND METHODS: Preoperative magnetic resonance imaging studies of nine pediatric patients with histologically confirmed medulloblastomas (eight desmoplastic medulloblastoma, and one giant cell medulloblastoma) were retrospectively reviewed, considering demographics as well as tumorscharacteristics such as localization, morphology, signal intensity, contrast-enhancement, dissemination, anddiffusion-weighted imaging and spectroscopy findings. RESULTS: In most of cases the tumors were centeredin the cerebellar vermis (77.8%), predominantly solid (88.9%), hypointense on T1-weighted images andintermediate/hyperintense on T2-FLAIR-weighted images, with heterogeneous enhancement (100%), tumor dissemination/extension (77.8%) and limited water molecule mobility (100%). Proton spectroscopy acquiredwith STEAM technique (n = 6) demonstrated decreased Naa/Cr ratio (83.3%) and increased Co/Cr (100%)and mI/Cr (66.7%) ratios; and with PRESS technique (n = 7) demonstrated lactate peak (57.1%). CONCLUSION: Macroscopic magnetic resonance imaging findings in association with biochemical features of medulloblastomas have been useful in the differentiation among the most frequent posterior fossa tumors. Keywords: Medulloblastoma; Infratentorial neoplasms; Pediatric brain tumors; Magnetic resonance imaging;Diffusion-weighted magnetic resonance imaging; Magnetic resonance spectroscopy.

Is brain SPECT a suitable modality for evaluation of postradiotherapy posterior fossa brain tumours? A comparative evaluation with contrast enhanced computed tomography.

Single photon emission computed tomography (SPECT) of the brain is exquisitely sensitive in detecting viable tumour tissue in the supratentorial region, but its efficacy has not been properly evaluated till date in case of infratentorial posterior fossa tumours. Twenty-four patients with primary posterior fossa brain tumour were included in this study. In each case brain SPECT with 99mTc-glucoheptonate (GHA) was performed for the evaluation of disease status. Contrast enhanced computerised tomography of brain was also performed in all the patients. Brain SPECT was positive in four patients with recurrence of tumour as compared to fifteen cases with computed tomography with a mean GHA retention index 5.26 +/- 1.64. Patients with postradiation gliosis (n=9) showed lower GHA retention index of 1.24 +/- 0.27. This study demonstrates that brain SPECT is not sensitive in detecting recurrence of tumour tissue in infratentorial region, as it is in the supratentorial region, with a sensitivity of 20%, accuracy of 45.83% and negative predictive value of 40% and the chance of any single study coming as false negative is about 80%.

Estudo por imagens convencionais e espectroscopia de prótons por ressonância magnética dos tumores da fossa posterior na faixa etária pediátrica / Magnetic resonance imaging and proton magnetic resonance spectroscopy of pediatric posterior fossa tumors

Objetivou-se descrever e comparar os tumores da fossa posterior na faixa etária pediátrica através dos achados das IRM e 1H ERM. Realizou-se seqüências pesadas em T1, T2FLAIR, T1 pós-Gd e PRESS com voxel único no tumor. Encontrou-se 14 casos de meduloblastoma, 8 de astrocitoma pilocítico e 5 de ependimoma. O meduloblastoma diferenciou-se dodemais pela sua localização, isossinal em T2, cistos de pequenas dimensões, maioresrelaçõesCo/Ce Co/NAA. Os ependimomas diferenciaram-se pela extensão pelos forames de Luschka e Magendie e cistos de médias dimensões. Os astrocitoma pilocíticos diferenciaram-se pelo realce anelar, edema perilesional, cistos grandes e maior relação NAA/Cr / This study objetives to describe and compare the pediatric posterior fossa tumors by MRI and 1H MRS. We performed sequences weighted on T1, T2, FLAIR, Gd-T1, and single voxel PRESS technique in the tumor. We found 14 cases of medulloblastoma, 8 of pilocytic astrocytoma and 5 of ependymoma. The medulloblastomas were different due to their localization, their isosignal on T2 sequence, the smallest cysts, higher Cho/Cr and Cho/NAA ratios. The ependymomas were different because their extension to the foramen Luschka and Magendie and medium size cysts. The pilocytic astrocytomas were different due to the anelar gadolinium-enhancement, perilesional edema, the largest cysts and higher NAA/Cr ratio...

Petroclival tumour surgery: a personal experience of 20 cases

petroclival lesions are amongst the most difficult lesions in Neurousrgery and carry a significant mortality and morbidity. However, over the last decade, publications from specialized centers have reported on the outcome of surgery for these lesions. we have analysed 20 patients, who had undergone surgery for petroclival tumour in general neurosurgical center over a 3-year-period [January 1997- December 1999]. there were 10 meningiomas, 5 chordomas, 3 trigeminal neurofibromas and 2 giant cell tumours. Seventeen patients had primary surgery while 3 had surgery for recurrent lesions. Investigations included CT scan, MRI and DSA or MRA in all patients. Ten patients were operated through retromastoid post-sigmoid approach, 7 through subtemporal combined with orbito-zygomatic approach and 3 were operated through combined retromastoid and subtemporal approach. There were two deaths. One was primarily related to surgery and the other due to respiratory complications. Six patients developed postoperative chest infection and 3 postoperative haematoma, of whom only 1 required surgical evacuation. Postoperative meningitis was recorded in 2 patients. Follow-up ranged from 9 months to 36 months with a mean of 21 months. None of the patients have, so far, developed recurrence or re-growth significant enough to merit a re-operation. tumour could not be removed totally in a significant number of cases inspite of all advances. Radiosurgery is an important adjuvant in the management of residual and recurrent lesions. Outcome was not different when compared to a specialized Neurousurgery unit

Supratentorial and infratentorial haemangioblastomas: literature review with lllustrative cases

The central nervous system haemangioblastomas are a unique group of life threatening, histologically benign tumours occurring solely within the neuroaxis. They are characterised by a familial incidence, a striking diversity of associated lesions in the organs and a gratifying response to microsurgical treatment. They are uncommon intracranial neoplasms constituting approximately 1 - 2% of intracranial masses and 7% of all infratentorial tumours. They may be associated with Von Hippel Lindau Complex [VHLC]. Among central nervous system haemangioblastomas, solitary or multiple, supratentorial haemangioblastomas are rare. They account for 2 - 8% of all haemangioblastomas. They are commonly intraparenchymatous, infrequently intraventricular and rarely in meningeal location. Interesting clinical, neuroradiological [computed tomography [CT] and magnetic resonance imaging [MRI]] findings are described in this review of literature with illustrative cases

Linfoma primario del sistema nervioso central: localizacion infratentorial y prolongada sobrevida / Primary CNS lymphoma: infratentorial localization and prolonged survival

Se describe el caso de una paciente de 35 años de edad, con linfoma primario del sistema nervioso central de localización infratentorial. Una inicial resonancia magnética (RM) reveló la lesión en bulbo, protuberancia, pedúnculos cerebelosos y vermis cerebeloso. Aunque durante el 1er año no se efectuó tratamiento, una posterior RM mostró menor extensión del tumor. Posteriormente la paciente recibió corticoides y 12 meses después, ya aceptada la biopsia estereot xica, pudo comprobarse un linfoma B difuso no Hodgkin. Se instituyó tratamiento radiante, llegando a una dosis total de 50 Gy. Durante 5 años la paciente tuvo una buena calidad de vida, con una sobrevida actual de 79 meses.

Cavernoma pontino / Pontine cavernoma

Os autores relatam um caso de uma paciente de 11 anos, com quadro súbito de síndrome cerebelar. Após realizada a Tomografia Computadorizada (CT) de crânio, constatou-se uma massa hiperdensa anterior ao quarto ventrículo e moderada hidrocefalia, sugerindo a presença de processo expansivo neoplásico. No transoperatório, constatou-se a presença de um hematoma intrapontino decorrente de uma malformaçao angiomatosa. Neste trabalho serao analisados o aspecto histotológico, o diagnóstico, as manifestaçoes clínicas, o tratamento e o prognóstico da malformaçao.

Refuerzo de la duramadre adyacente a los meningiomas luego de la administración de Gadolinio en RM: sensibilidad y especificidad / Reincenforcement of the dura adjacent to meningiomas after administration of Gd in MRI: sensitivity and specificity

Los autores evalúan el valor de la administración de Gd DTPA en el diagnóstico de meningiomas madiante RM en un estudio restrospectivo sobre 184 pacientes con masas tumorales de diferentes etiologías, de los cuales 14 eran meningiomas confirmados por cirugía. La edad promedio de los pacientes fue de 62.7 años. Los resultados confirman que en estos casos la toma de Gd DTPA en RM de la duramadre en base a la implantación de la masa tumoral, constituye un signo de valor diagnóstico importante, que en esta serie tuvo una sensibilidad y especificidad del 100

Diagnóstico tomográfico de los tumores endocraneales / Computed tomographic evaluation of brain neoplasms

De 14.386 estudios tomográficos realizados entre enero de 1989 y junio de 1992, 7.146 fueron de cerebro. Dentro de este grupo, 390 pacientes presentaron patología tumoral encefálica. De 130 pacientes se obtuvo confirmación histológica del tumor, correlacinando los datos obtenidos de acuerdo a edad, sexo y localización de la lesión y las variantes histológicas halladas