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Vol.9, Issue 1; January-February 2024; 

ISSN: 2994-0524  

Impact Factor: 6.14 

1252 Columbia Rd NW, Washington DC, United States 

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UNCHARTED TERRITORY: EXPLORING MEDULLOBLASTOMA IN THE 

CEREBELLOPONTINE ANGLE OF A TODDLER – A SINGULAR CASE 

STUDY 
  
1Rafael M. Santos and Carla A. Silva2 
1Department of Neurosurgery, Hospital Regional do Baixo Amazonas Dr. Waldemar Penna, Santarém, Pará, 

Brazil 
2Department of Neurosurgery, Hospital Regional do Baixo Amazonas Dr. Waldemar Penna, Santarém, Pará, 

Brazil    

DOI: https://doi.org/10.5281/zenodo.10598161 
 

 

 

 Abstract  

Medulloblastomas (MB) are malignant embryonic neuroepithelial tumors of the cerebellum, accounting 

Medulloblastomas, predominant childhood tumors, account for a substantial portion of Central Nervous System 

neoplasms in the first decade of life. Originating from embryonic and undifferentiated neuroepithelial cells within 

the cerebellum, particularly the cerebellar vermis, these tumors are intricately linked to the external granular 

layers of the cerebellar hemispheres (Millard and De Braganca, 2016; Valtz et al., 1991). This research aims to 

elucidate the unique manifestation of medulloblastoma in the cerebellopontine angle (CPA), an uncommon 

occurrence with sparse documentation in the literature, primarily observed in the adult population. 

The embryological association of medulloblastomas with the external granular layers of the cerebellum and 

germinal cell remnants in the posterior medullary velum provides a foundation for understanding their prevalence 

in pediatric cases (Millard and De Braganca, 2016; Valtz et al., 1991). Proper classification of these tumors stems 

from their origin in embryonic and undifferentiated neuroepithelial cells, accentuating their affiliation with the 

cerebellar vermis (Rutka and Hoffman, 1991; Jakacki, 2005; Gajjar et al., 2004). 

In contrast, medulloblastoma occurrences in the cerebellopontine angle are infrequent, with limited documented 

cases primarily observed in the adult demographic, constituting up to 75% of cases within this age group 

(Noiphithak et al., 2016; Faried et al., 2016). Notably, adult medulloblastomas in the CPA display distinctive 

characteristics, predominantly lateral localization in the cerebellar hemispheres, axial positioning, cystic 

formations, and ill-defined margins, often extending to the fourth ventricular foramen (Taylor et al., 2012; Helseth 

et al., 1999; Savardekar et al., 2012). 

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 American Journal of Medical and Physical Education  

Vol.9, Issue 1; January-February 2024; 

ISSN: 2994-0524  

Impact Factor: 6.14 

1252 Columbia Rd NW, Washington DC, United States 

https://topjournals.org/index.php/AJMPE; mail: topacademicjournals@gmail.com 

 
 

 

 

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This research endeavors to contribute to the limited body of knowledge on medulloblastomas in the 

cerebellopontine angle, providing insights into the unique features and challenges associated with this rare 

manifestation in the adult population. 

Keywords: Medulloblastomas, Cerebellopontine Angle, Central Nervous System Tumors, Pediatric 

Neurooncology, Adult Neurosurgery  

  

INTRODUCTION  

Medulloblastomas are common childhood tumors, especially in the first decade of life, representing 25% of all 

tumors of the Central Nervous System in this age group. Embryologically related with external granular layers of 

the cerebellar hemispheres, either with germinal cells remnants located at posterior medullary velum (Millard and 

De Braganca, 2016; Valtz et al., 1991). The proper tumor classification is due to embryonic and undifferentiated 

neuroepithelial cells from the cerebellum, especially the cerebellar vermis (Rutka and Hoffman, 1991; Jakacki, 

2005; Gajjar et al., 2004).  

In turn, medulloblastoma in CPA are uncommon, with rare reports in the literature, these mainly related to the 

adult population, representing up to 75% of the population group reaching the disease (Noiphithak et al., 2016; 

Faried et al., 2016). In adults, medulloblastomas is predominantly lateral located in the cerebellar hemispheres, 

in comparison with the axial position, with cystic formation and ill-defined margins, extending to the fourth 

ventricular foramen (Taylor et al., 2012; Helseth et al., 1999; Savardekar et al., 2012).  

The diagnosis is made by neuroimaging exams and  

2 Med. Case Stud. 

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 American Journal of Medical and Physical Education  

Vol.9, Issue 1; January-February 2024; 

ISSN: 2994-0524  

Impact Factor: 6.14 

1252 Columbia Rd NW, Washington DC, United States 

https://topjournals.org/index.php/AJMPE; mail: topacademicjournals@gmail.com 

 
 

 

 

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Figure 1. T1-weighted coronal section of magnetic resonance imaging showing a lesion with sharp limits, located 

in the right cerebellopontine angle that displaces and deforms the brain stem and the right cerebellar hemisphere.

Confirmed by means of histopathology and immunohistochemistry techniques, presenting great difficulty in the 

neuroradiological differential diagnosis when compared with vestibular meningiomas and schwannomas. 

Treatment consists of surgical resection, when possible, followed by chemotherapy, however an early diagnosis 

is necessary for a better prognosis (Faried et al., 2016; Spina et al., 2013; Bhaskar et al., 2017). The present study 

aims to report a clinical case of medulloblastoma in the pontocerebellar angle and thus contribute to scientific 

knowledge on this topic.   

MATERIALS AND METHODS  

Report of a single case of a patient seen at the Regional Hospital of Baixo Amazonas Dr. Waldemar Penna, 

Santarém, Pará. The data were collected through the analysis of the patient's medical record, having access to the 

data contained therein such as medical developments, laboratory tests, exams imaging and histopathological.  

CASE REPORT  

Clinical history  

A   one-year-old   male   patient   attended in a  pediatric  service with a history of facial weakness. After the initial 

analysis, he was referred to the oncology and neurosurgery services, being admitted for clinical followup. The 

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 American Journal of Medical and Physical Education  

Vol.9, Issue 1; January-February 2024; 

ISSN: 2994-0524  

Impact Factor: 6.14 

1252 Columbia Rd NW, Washington DC, United States 

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patient evolved with progressive neurological disfunction, presenting Glasgow 15 with right hemifacial paresis, 

followed by cyanosis, mydriatic pupil and associated dysphagia.  

Imaging, myelogram, histopathological and immunohistochemical exams  

The initial approach involved the screening for neurological tumors and after the confirmation, was realized the 

tumor staging. Cerebral magnetic resonance imaging (Figures 1 and 2) was performed, showing a lesion located 

in the right cerebellar cistern, with displacement and deformation of the brain stem and the right cerebellar 

hemisphere. Figure 3 shows a penetrating lesion in the internal auditory canal, with full canal filling and dilation 

of the internal auditory canal. Magnetic resonance imaging of vertebral column showed no abnormality.  

The myelogram exam showed 37% of mature lymphocytes, 1% of monocytes and 6% of medium to large cells, 

with fine chromatin, Grumpetch’s nuclear       shadow,       absent     granules     and     high  

Magalhães et al. 3 

  
Figure 2. T2-weighted coronal section of magnetic resonance imaging showing a hypertense lesion in the region 

of the right cerebellopontine angle with a mass effect on the brainstem.  

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 American Journal of Medical and Physical Education  

Vol.9, Issue 1; January-February 2024; 

ISSN: 2994-0524  

Impact Factor: 6.14 

1252 Columbia Rd NW, Washington DC, United States 

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Figure 3. Axial magnetic resonance imaging, T1-weighted hypertense homogenous extra-axial image. The lesion 

penetrates the internal ear canal, filling it completely and dilating the internal auditory canal.  

4          Med. Case Stud. 

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 American Journal of Medical and Physical Education  

Vol.9, Issue 1; January-February 2024; 

ISSN: 2994-0524  

Impact Factor: 6.14 

1252 Columbia Rd NW, Washington DC, United States 

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Figure 4. (A) Histopathological analysis - Increased parallel alignment of neoplastic nuclei in rows. (A) 

Histopathological analysis - Increased parallel alignment of neoplastic nuclei in rows "or rhythmic palisades". 

There are also Homer Wright's pseudorosettes and fat cells. (B) Immunohistochemistry analysis - GFAP positivity 

in tissue suggests malignant lesion. (C) Immunohistochemistry analysis - CD99 staining is predominantly noticed 

on cell membranes and here we see positivity in different sections of the tumor suggesting  

medulloblastoma.  

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 American Journal of Medical and Physical Education  

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ISSN: 2994-0524  

Impact Factor: 6.14 

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nuclecytoplasmatic ratio.  

The histopathological result (Figure 4A) showed tumor cells arranged in Homer Wright's pseudorosettes, 

morphologically classified as classic medulloblastoma. Which are dense cellular neoplasms, consisting of  small,  

oval cells with a high nucleus/cytoplasm ratio. Immunohistochemistry (Figure 4B and C) showed positivity for 

glial fibrillary acid protein (GFAP) and CD99. In addition to positivity for synaptophysin, beta catenin, and    KI-

67,   genetically   classified   as   WNT-activated medulloblastoma. Using histopathology and 

immunohistochemistry information, the diagnosis of medulloblastoma was established, based on guidelines 

(Pietsch and Haberler, 2016).  

Therapeutic conduct and outcome  

 After diagnosis, the patient underwent tumor resection at a right cerebellar point angle, by retrosigmoid approach, 

without complications and no need of ventricular shunt technique. Surgical procedure was subsequently 

accompanied by an oncological therapeutic plan based on three cycles of chemotherapy, with methotrexate, 

vincristine and cyclophosphamide. However, after 21 days of the surgical procedure, the patient progressed to a 

coma, followed by multiple organ failure related with neurogenic shock, until the diagnosis of brain death was 

confirmed.   

DISCUSSION  

MB is a highly malignant and aggressive neuroectodermal tumor of cerebellar origin, densely cellular and distinct 

from sarcomas and other gliomas. The current literature considers it as a common pediatric tumor of the posterior 

fossa representing 20-25% of all pediatric tumors, which develop in the cerebellar vermis and in the fourth 

ventricle. It can be found in the midline, in the cerebellar hemisphere or in the CPA. In adults and children, the 

most common location is the cerebellar hemisphere, with CPA being an extremely rare variant (Spina et al., 2013; 

Batista et al., 2017).  

The epidemiological profile of the tumor, considering the higher prevalence in the first decade of life, is explained 

by its embryonic characteristic. Clusters of neuroepithelial cells from the roof of the fourth ventricle can migrate 

to make the composition of the outer granular layer of the cerebellum. Migratory cells can remain resident until 

the first year of age, being related to the appearance of medulloblastomas in any part of the migratory path of 

these cells (Rubinstein, 1972; Zimmerman et al., 1978). The rare location in CPA makes MB an unusual 

differential diagnosis of tumors that affect the appropriate area, with the most frequent differentials in relation to 

MB: Lymphomas, schwannoma, meningioma, primary cholesteatomas and epidermoid tumors. Vestibular 

schwannomas and meningiomas are the two most frequent lesions and represent 90% of all tumors in CPA (Batista 

et al., 2017)  

Imaging findings have variable and non-specific characteristics, making it difficult to differentiate, giving 

preference to histopathological and immunohistochemical diagnosis. The appearance of medulloblastoma on 

magnetic resonance imaging usually manifests itself with hypo-intensity on T1-weighted images and 

heterogeneous hyperintensity on T2-weighted images and improves with Magalhães et al. 5  

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conrasts (Faried et al., 2016; Bhaskar et al., 2017; Batista et al., 2017; Nyanaveelan et al., 2007). 

Histopathologically, classic medulloblastoma contains small individual cells with scarce cytoplasm and 

hyperchromatic nuclei that are often elongated. The tumor may express neurosecretory granules or Homer Wright 

rosettes. The characteristic immunohistochemistry reveals positivity for synaptophysin with variable reactivity to 

GFAP, β-catenin, membrane epithelial antigen and cytokeratin (Pietsch and Haberler, 2016).  

In our report, the results showed tumor reactivity to synaptophysin and GFAP. Synaptophysin is an integral 

membrane glycoprotein from presynaptic vesicles of neuronal and neuroendocrine cells that has been identified 

as a reliable marker for neuronal differentiation, which is commonly seen in medulloblastoma. GFAP is an 

intermediate astroglial cytoskeletal protein that is commonly expressed in neural stem cells (Noiphithak et al., 

2016; Faried et al., 2016; Bhaskar et al., 2017). The preoperative clinical history showed an atypical symptom of 

right hemifacial weakness and absence of classical symptoms. The literature shows classic symptoms of MB as 

irritability, lethargy, nausea and vomiting, morning headaches, anorexia, behavioral changes and seizures. The 

finding is important, since demonstrates the atypical presentation of the clinical case reported (Millard and De 

Braganca, 2016).  

As for treatment, total removal with adjuvant radiotherapy is commonly performed as therapy, when age and 

other prerequisites permits. Chemotherapy has also been combined in some cases, as the residual tumor is 

associated with worse progression. However, Pant et al. (2016) states that aggressive brain tumor removal is not 

recommended, since a high rate of postoperative complications have been reported after tumor resection. Thus, 

the outcome of MB treatment in the CPA is not well established due to limited reports, because despite the 60 to 

70% increase in survival, attributed to improvements in surgical techniques and adjuvant therapies, more cases 

are still needed to confirm these discoveries (Noiphithak et al., 2016; Spina et al., 2013).  

CONFLICT OF INTERESTS  

The authors have not declared any conflict of interests.  

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Impact Factor: 6.14 

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 American Journal of Medical and Physical Education  

Vol.9, Issue 1; January-February 2024; 

ISSN: 2994-0524  

Impact Factor: 6.14 

1252 Columbia Rd NW, Washington DC, United States 

https://topjournals.org/index.php/AJMPE; mail: topacademicjournals@gmail.com 

 
 

 

 

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