Medulloblastoma, calcified

CLINICAL HISTORY:
This 13-year old girl complains of 6 months of repeated headaches and vomiting. Now she notes blurred vision, disequilibrium, gait instability and a general feeling of weakness.

NEUROLOGICAL EXAMINATION reveals bilateral papilledema. The gait is unstable, and there is dysmetria.

CONTRAST-ENHANCED CT (IMAGE 1 AND 2): A huge midline posterior fossa relatively well-circumscribed mass is identified. The mass is extensively calcified (arrows) and shows moderate contrast enhancement. The fourth ventricle is displaced anteriorly.

MRI:
a) TRANSAXIAL T2-WEIGHTED (3800/85/1) SPIN-ECHO SEQUENCE (IMAGE 3): The mass is seen in the midline in the posterior fossa. The lesion is diffusely hyperintense, with flecks of calcification scattered throughout the lesion. The fourth ventricle (arrowheads) is displaced anteriorly.

b) TRANSAXIAL T1-WEIGHTED (680/20/1) SPIN-ECHO SEQUENCE (IMAGE 4): The lesion now is hypointense.

c) TRANSAXIAL (IMAGE 5), CORONAL (IMAGE 6) AND SAGITTAL (IMAGE 7) GADOLINIUM-ENHANCED SPIN-ECHO SEQUENCES: There is moderate but rather homogeneous enhancement of the tumor. The tumor is situated in the midline and extends inferiorly to the brainstem (arrows). Laterally the tumor invades the cerebellum bilaterally. The fourth ventricle (arrowhead) is displaced in an anterior and upward direction.

RADIOLOGICAL DIFFERENTIAL DIAGNOSIS is between medulloblastoma and ependymoma. The lesion is in the midline and could originate from the vermis or be centered in the fourth ventricle. Calcifications are more frequently seen in ependymoma.

SURGICAL FINDINGS: At surgery, a tumor of the vermis was found. The resection was subtotal because the tumor infiltrated the medulla oblongata and the inferior cerebellar peduncles bilaterally. The lateral wall of the fourth ventricle was also infiltrated.

ANATOMOPATHOLOGY was consistent with medulloblastoma.

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Medulloblastoma

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