Figure 1
Unenhanced CT head showing a midline isodense mass in the posterior fossa with hydrocephalus.
Gyriform differentiation in medulloblastoma
SectionPaediatric radiology
Case TypeClinical Cases
Authors
Juvaina P, Rajendran VR, Devarajan E, Alappat JP, Naufal P.
Dept. of Radiodiagnosis, Calicut Medical College, Calicut, India.
Connected authors
2 years, male
Clinical History
A 2-year-old boy presented with unsteadiness of gait and projectile vomiting of 3 months duration.
Imaging Findings
This 2-year-old male patient presented with unsteadiness of gait and projectile vomiting. On examination he was drowsy. Motor examination revealed good spontaneous movements and tone with intact sensation bilaterally.
Unenhanced CT head scan revealed massive hydrocephalus with a large midline
isodense tumour mass in the posterior fossa (Fig. 1). An emergency ventriculoperitoneal shunt was created. A contrast MRI done subsequently showed a large midline mass in the posterior fossa which was elevating the tentorium and displacing the brain stem anteriorly as well as the cerebellar hemispheres laterally. The mass had a striking gyriform appearance, appearing isointense to grey matter on T1 and T2 weighted images (Figs. 2, 3) and showed mild post contrast enhancement (Fig. 4). MR spectroscopy revealed a high choline and low NAA peak compatible with a neoplasm (Fig. 5). Diffusion weighted MR revealed restricted diffusion compatible with high cellularity of the tumour (Fig. 6). Intraoperatively, each nodular mass could be resected individually and a gross total excision of the tumour was done. Histopathological report came as medulloblatoma with extensive noularity (desmoplastic variant).
Unenhanced CT head scan revealed massive hydrocephalus with a large midline
isodense tumour mass in the posterior fossa (Fig. 1). An emergency ventriculoperitoneal shunt was created. A contrast MRI done subsequently showed a large midline mass in the posterior fossa which was elevating the tentorium and displacing the brain stem anteriorly as well as the cerebellar hemispheres laterally. The mass had a striking gyriform appearance, appearing isointense to grey matter on T1 and T2 weighted images (Figs. 2, 3) and showed mild post contrast enhancement (Fig. 4). MR spectroscopy revealed a high choline and low NAA peak compatible with a neoplasm (Fig. 5). Diffusion weighted MR revealed restricted diffusion compatible with high cellularity of the tumour (Fig. 6). Intraoperatively, each nodular mass could be resected individually and a gross total excision of the tumour was done. Histopathological report came as medulloblatoma with extensive noularity (desmoplastic variant).
Discussion
Posterior fossa tumors comprise 50% of pediatric brain tumors.Cerebellar astrocytomas, medulloblastomas and ependymomas present with symptoms of raised intra cranial pressure and ataxia. Brain stem gliomas involve the cranial nerve nuclei and long tracts at an early stage[4].
Cerebellar astrocytoma-20-25% of posterior fossa tumors.Vermis(50%)or hemispheres(20%) or both sites(30%)+/- extension into cavity of 4th ventricle.Calcification in 20%. 80% are juvenile pilocytic astrocytomas with a cyst with enhancing isodense mural nodule in CT[4].
Medulloblastoma-30-40% of posterior fossa tumors.Short history.80% located in Vermis;30%extend into the brain stem.calcification in 10-15%.CT shows a well defined hyper dense homogeneously enhancing solid lesion with effacement of 4th ventricle.CSF dissemination and extra cranial metastasis to bone ,lymph nodes and soft tissue can occur[4].
Ependymoma-8-15% of posterior fossa tumors .Usually a long clinical history.CT shows an iso dense to hyper dense 4th ventricular mass with punctate calcifications,small cysts and heterogeneous contrast enhancement[4].calcification in 46-50%.MRI demonstrates tumor extension through the foramen of Magendie and foramen of Luschka.
Brain stem glioma-20-30% of posterior fossa tumors.Four sub groups:(a)medullary,(b)pontine,(c)mesencephalic and (d)those associated with NF1.Tumors may also be diffuse (>50-75% of the brain stem in the axial plane ) or focal(<50%).Calcification rare[4].
Medulloblastomas characterized by extreme nodularity, intranodular nuclear uniformity and cell streaming in a fine fibrillary background have been termed
‘medulloblastoma with extensive nodularity (MBEN)’, and could represent a subgroup of the nodular/ desmoplastic variety of medulloblastoma [1]. On MRI, the tumour has a remarkable grape like or gyriform appearance [1, 3], which might represent extreme differentiation of the tumour cells into a nodular pattern representing ‘gyri’ or ‘grapes’. This characteristic MRI imaging, by giving a clue to the histological subtype preoperatively, may encourage a more aggressive management of these tumours.
These tumours apparently have better prognosis then other types of medulloblastoma [4], and in one of the largest series consisting of 11 children with MBEN, all were alive at a median follow up of 66 months, with five being considered cured [1]. None of these children, however, had evidence of tumour dissemination at diagnosis.
This case emphasizes the importance of rapid neuroimaging in case of unexplained vomiting in children.
Cerebellar astrocytoma-20-25% of posterior fossa tumors.Vermis(50%)or hemispheres(20%) or both sites(30%)+/- extension into cavity of 4th ventricle.Calcification in 20%. 80% are juvenile pilocytic astrocytomas with a cyst with enhancing isodense mural nodule in CT[4].
Medulloblastoma-30-40% of posterior fossa tumors.Short history.80% located in Vermis;30%extend into the brain stem.calcification in 10-15%.CT shows a well defined hyper dense homogeneously enhancing solid lesion with effacement of 4th ventricle.CSF dissemination and extra cranial metastasis to bone ,lymph nodes and soft tissue can occur[4].
Ependymoma-8-15% of posterior fossa tumors .Usually a long clinical history.CT shows an iso dense to hyper dense 4th ventricular mass with punctate calcifications,small cysts and heterogeneous contrast enhancement[4].calcification in 46-50%.MRI demonstrates tumor extension through the foramen of Magendie and foramen of Luschka.
Brain stem glioma-20-30% of posterior fossa tumors.Four sub groups:(a)medullary,(b)pontine,(c)mesencephalic and (d)those associated with NF1.Tumors may also be diffuse (>50-75% of the brain stem in the axial plane ) or focal(<50%).Calcification rare[4].
Medulloblastomas characterized by extreme nodularity, intranodular nuclear uniformity and cell streaming in a fine fibrillary background have been termed
‘medulloblastoma with extensive nodularity (MBEN)’, and could represent a subgroup of the nodular/ desmoplastic variety of medulloblastoma [1]. On MRI, the tumour has a remarkable grape like or gyriform appearance [1, 3], which might represent extreme differentiation of the tumour cells into a nodular pattern representing ‘gyri’ or ‘grapes’. This characteristic MRI imaging, by giving a clue to the histological subtype preoperatively, may encourage a more aggressive management of these tumours.
These tumours apparently have better prognosis then other types of medulloblastoma [4], and in one of the largest series consisting of 11 children with MBEN, all were alive at a median follow up of 66 months, with five being considered cured [1]. None of these children, however, had evidence of tumour dissemination at diagnosis.
This case emphasizes the importance of rapid neuroimaging in case of unexplained vomiting in children.
Differential Diagnosis List
Medulloblastoma with extensive nodularity[MBEN].
Final Diagnosis
Medulloblastoma with extensive nodularity[MBEN].
References
[1] Giangaspero F, Perilongo G, Fondelli M P, Brisigotti M, Carollo C, Burnelli R, Burger P C, Garre M L (1990) Medulloblastoma with extensive nodularity: a variant with favorable prognosis. Journal of Neurosurgery 91:971-977 (PMID: 10584843)
[2] Yamamoto Y & Ohmoto T (2000) Nodular medulloblastoma. Journal of Neurosurgery 93, 723- 724 (PMID: 11014561)
[3] Suresh TN, Santosh V, Yasha TC, Anandh B, Mohanty A, Indiradevi B, Sampath S & Shankar SK. (2004) Medulloblastoma with extensive nodularity: a variant occurring in the very young-clinicopathological and immunohistochemical study of four cases. Childs Nerv Syst 20:55-60 (PMID: 14657995)
[4] Stephen Chapman,Richard Nakielny (4th) AIDS TO RADIOLOGICAL DIFFERENTAIL DIAGNOSIS.
Case information
| URL: | https://www.eurorad.org/case/8511 |
| DOI: | 10.1594/EURORAD/CASE.8511 |
| ISSN: | 1563-4086 |
Figure 2
T1weighted MR image showS the lesion to be isointense to gray matter.
Figure 3
Gadolinium enhanced MR image shows no significant enhancement of the lesion.
Figure 4
T2 weighted MR image shows the lesion to be isointense to gray matter.
Unenhanced CT head showing a midline isodense mass in the posterior fossa with hydrocephalus.
T1weighted MR image showS the lesion to be isointense to gray matter.
Gadolinium enhanced MR image shows no significant enhancement of the lesion.
T2 weighted MR image shows the lesion to be isointense to gray matter.
