Case contributed by Frank Gaillard
Diagnosis certain



Patient Data

Age: 40 years
Gender: Female

A hyperdense, heterogeneously enhancing mass is located in the midline in the roof of the 4th ventricle and results in hydrocephalus. 


Centered within the fourth ventricle and arising either from within the ventricle or from the ventral aspect of the vermis is a 3 cm diameter mass which appears moderately hyperintense on T2, intermediate to low signal on T1, and demonstrates heterogeneous contrast enhancement. No calcification. The mass demonstrates moderate restricted diffusion. High T2 signal (edema) extends into the parenchyma of the vermis, but not into the pons.

It is surrounded by a number of small peritumoural cysts particularly posterolaterally. Prominent right PICA passes through the mass, best seen on axial T2 weighted imaging.

The ventricles are prominent with a mild degree of transependymal edema consistent with a degree of hydrocephalus.

The infundibulum of the pituitary gland appears somewhat thickened and vividly enhancing, raising the possibility of abnormal nodular enhancement of this location.

The remainder of the brain is unremarkable with no intra or extra-axial abnormality.


Despite the patient's age, the location and apparent high cellularity (diffusion restriction) favors the diagnosis of a medulloblastoma. 

MRI spine


Selected images from MRI whole spine demonstrate extensive linear and to a lesser extent the nodular enhancement lining the majority of the spinal cord, from the cervicomedullary junction to the nerve roots of the cauda equina. Close to the most discrete nodule, which lies at lower T3 level and measures 4 x 7 x 8 mm, the upper thoracic spinal cord from lower T1 to upper T4 level exhibits high T2 signal and mild expansion.

Case Discussion

The patient went on to have the posterior fossa mass resected. 



Paraffin sections show fragments of a densely hypercellular tumor. Tumor cells have markedly pleomorphic nuclei, some with delicate processes and are arranged predominantly in diffuse sheets in a fibrous stroma. Scattered Homer-Wright rosettes are noted. An occasional mitotic figure is identified. There is no microvascular proliferation and no necrosis is seen. Attachment of leptomeninges is noted. The tumor cells are diffusely synaptophysin and CD56 positive.

There is patchy staining for NeuN and GFAP. AE1/3 and IDH-1 are negative. The topoisomermase index is about 25%.

DIAGNOSIS: Medulloblastoma (WHO Grade IV)

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