Computerized tomographic findings in medulloblastomas

Extra-axial medulloblastoma in the cerebellar hemisphere

Extra-axial medulloblastoma is a rare phenomenon. We report a case in a 5-year-old boy who presented with nausea, vomiting, and gait disturbance. He was treated with total removal of the tumor. This is the first case of an extra-axially located medulloblastoma occurring in the cerebellar hemisphere posteriolateral to the cerebellopontine angle in Korea. Although the extra-axial occurrence of medulloblastoma is rare, it should be considered in the differential diagnosis of extra-axial lesions of the posterior fossa in children.

Distinctive MRI features of pediatric medulloblastoma subtypes

OBJECTIVE

We hypothesized that the apparent diffusion coefficient (ADC) and other MRI features can be used to predict medulloblastoma histologic subtypes, as defined by the World Health Organization (WHO) in WHO Classification of Tumours of the Central Nervous System.

MATERIALS AND METHODS

A retrospective review of pediatric patients with medulloblastoma between 1989 and 2011 identified 38 patients with both pretreatment MRI and original pathology slides. The mean and minimum tumor ADC values and conventional MRI features were compared among medulloblastoma histologic subtypes.

RESULTS

The cohort of 38 patients included the following histologic subtypes: 24 classic medulloblastomas, nine large cell (LC) or anaplastic medulloblastomas, four desmoplastic medulloblastomas, and one medulloblastoma with extensive nodularity. The median age at diagnosis was 8 years (range, 1-21 years) and the median follow-up time was 33 months (range, 0-150 months). The mean ADC (× 10(-3) mm(2)/s) was lower in classic medulloblastoma (0.733 ± 0.046 [SD]) than in LC or anaplastic medulloblastoma (0.935 ± 0.127) (Mann-Whitney test, p = 0.004). Similarly, the minimum ADC was lower in classic medulloblastoma (average ± SD, 0.464 ± 0.056) than in LC or anaplastic medulloblastoma (0.630 ± 0.053) (p = 0.004). The MRI finding of focal cysts correlated with the classic and desmoplastic subtypes (Fisher exact test, p = 0.026). Leptomeningeal enhancement positively correlated with the LC or anaplastic medulloblastoma subtype and inversely correlated with the classic medulloblastoma and desmoplastic medulloblastoma subtypes (p = 0.04). Ring enhancement correlated with tumor necrosis (p = 0.022) and with the LC or anaplastic medulloblastoma histologic subtype (p < 0.001).

CONCLUSION

The LC or anaplastic medulloblastoma subtype was associated with increased ADC and with ring enhancement, the latter of which correlated with tumor necrosis. These features could be considered in the evaluation of high-risk medulloblastoma subtypes.

Cerebellopointine angle medulloblastoma

Cerebellopontine angle (CPA) medulloblastoma is a rare tumour. To date, only 19 cases have been reported over a period of 8 years, we have treated 14 cases of CPA medulloblastomas. This is first and the largest series of CPA medulloblastomas reported in the world literature.

Central nervous system medulloepithelioma: a series of eight cases including two arising in the pons

Medulloepithelioma is an uncommon childhood tumor of the central nervous system (CNS) whose histopathological appearance has been confused with medulloblastoma and other childhood primitive neuroectodermal tumors (PNETs), but which has a vastly different clinical course. The authors have reviewed the clinical features and treatment responses of eight children with these rare tumors, the largest series to date. In this series, the medulloepitheliomas were equally distributed between supratentorial and infratentorial primary sites. Four patients underwent gross- or near-total resections, one patient's tumor was partially resected, and one patient had biopsy only. Biopsy and ablative surgery were not attempted in two children with pontine tumors. Treatment included both radiation and chemotherapy (four patients), radiation alone (one patient), chemotherapy alone (one patient), and no post-operative treatment (two patients). Six patients died with a mean survival of 10 months and two are disease free with neurological impairment. Both long-term survivors underwent gross-total resections of their tumors. Postmortem examination revealed diffuse CNS tumor dissemination in four patients. Medulloepithelioma, often confused with less aggressive PNETs, can mimic intrinsic brainstem glioma, responds poorly to treatment, and is prone to CNS dissemination at the time of tumor progression.

Adult medulloblastoma: review of 13 cases with emphasis on MRI

Medulloblastomas are generally associated with childhood, but 14-30% occur in adults, accounting for 1% of adult central nervous system tumors. While approximately one third of adult medulloblastomas present as vermian tumors similar to those seen in childhood, the majority differ substantially from the childhood variety. In this series of 13 patients, 5 had lateral, seemingly extra-axial masses in the cerebellopontine angle or at the tentorium, simulating meningiomas or acoustic neuromas, but angiographic hypovascularity in 2 of the latter suggested a diagnosis other than meningioma. Of 4 paramedian tumors, 3 diffusely infiltrated the cerebellar white matter, showed little or no gadolinium enhancement and were not associated with hydrocephalus. Hydrocephalus was present in less than half of our patients; in childhood the reported incidence is 85-100%. A possible association with pregnancy was noted.

Cerebellopontine angle medulloblastoma: case report and literature review

The occurrence of cerebellopontine angle (CPA) medulloblastoma is a rare phenomenon. We report such a case in a 19-year-old girl who had 6th and 8th cranial nerve palsies as well as cerebellar dysfunction. The tumour arose from the left flocculus or adjacent cerebellar hemisphere and projected into the CPA. She was treated by subtotal removal of the tumour, followed by entire neuroaxis irradiation and immunochemotherapy. The clinical characteristics and pathogenesis of CPA medulloblastoma are reviewed and discussed.

Computed tomography in intracranial, supratentorial metastases in children

This study compares the CT characteristics in a consecutive sample of supratentorial metastases (n = 31) with primary tumors of the same location (n = 49) in childhood. Postcontrast CT was performed in all but one of the metastases cases. In all but one of these children the location and type of primary tumor was known at time of occurrence of cerebral metastasis. Primary CNS tumors (n = 12) had a higher incidense of supratentorial metastatic spread than tumor originating elsewhere. Three children had diffuse subarachnoid seeding, while 28 had solid tumors (21 solitary, 7 multiple). The predilection location for the solid metastases was the gray-white matter junction (n = 12). The following CT findings were significantly less frequent in metastases than in primary tumors (P less than 0.05): Midline location, calcification and cyst formation. On the other hand bleeding, pronounced contrast enhancement and location in the gray-white matter junction were more frequent in the metastatic group (P less than 0.05).

Computed tomography in management of medulloblastomas

The neuroradiological studies of 116 patients with histologically verified medulloblastomas, which had been examined with plain and contrast-enhanced computed tomography (CT), were reviewed. The typical CT appearances of a well-defined, hyperdense enhancing mass in the vermis, with surrounding oedema, occurred in 60% of this series. Atypical features include calcification (17%), cystic or necrotic regions (47%) or poorly defined margins and lack of enhancement (7%). Such features in a vermis mass presenting in the first decade, especially in a boy, should not be considered against the diagnosis of medulloblastoma, but may be misleading when the tumour predominantly involves a cerebellar hemisphere.

Posterior fossa lesions in childhood and infancy. A CT study

Forty-three children with CT studies demonstrating abnormalities in the posterior fossa are presented. Tumors constitute the largest group of lesions (53.5%). Their mean size at time of diagnosis was 39.5 mm. Astrocytomas, medulloblastomas, and ependymomas were the most frequent tumors and their CT features are described and discussed. The congenital group of lesions comprised 18.6% of the cases--the most frequent anomaly being arachnoid cyst. In the miscellaneous group (23.3%), cases with atrophy were the most frequent. The cerebellar hemispheres were the most involved sites (39.5%). Lesions located at the tentorial hiatus or near the clivus were rather rare.

Cystic adult medulloblastomas

The computed tomography scans of four patients who had a medulloblastoma are reviewed. In all the cases, atypical findings were present--specifically, cystic or lucent areas within the tumor. The importance of this uncommon finding associated with adult medulloblastoma is discussed.

Medulloblastomas: a review of modern management with a report on 75 cases

The authors summarize the 8-year experience of a tertiary medical center with 75 cases of medulloblastoma in Saudi Arabia. A discussion of the evolution of modern management of this difficult problem ensues. As 5-year survival statistics approach 80% in some institutions, attention is being focused on the long-term effects of modern therapy and the quality of life led by these children.