Medulloblastoma - SHH subgroup

Case contributed by Dr Henry Knipe

Presentation

Upper limb numbness.

Patient Data

Age: 30 years
Gender: Female
CT

Left cerebellar mass with surrounding vasogenic oedema with mild mass effect of the fourth ventricle. 

MRI

Intra axial left cerebellar mass is T1 hypointense, T2 hyperintense with central foci of cystic change and demonstrates homogeneous enhancement. Moderate amount of surrounding FLAIR hyperintensity but no significant mass-effect with pain in fourth ventricle and no hydrocephalus. The enhancing components demonstrate homogeneous diffusion restriction (ADC 560).

Suggestion of a tiny focus of leptomeningeal enhancement of the adjacent posterior vermis. No susceptibility artefact on SWI. No other mass lesion is identified.

Minimally increased CBV within the centre of the mass.

Pathology

MICROSCOPIC DESCRIPTION: All the sections show a densely cellular malignant tumour, adjacent to cerebellar cortex. It has a nodular architecture with scattered pale islands. The tumour cells have high N/C ratio with elongated and hyperchromatic nuclei, nuclear moulding, focal prominent nucleoli and scanty cytoplasm. Within the nodules, the tumour cells are more widely spaced and with more fibrillary matrix. Scattered mitoses are seen, along with apoptotic debris. The features are those of desmoplastic/nodular medulloblastoma. The reticulin stain shows fibres in-between the nodules but absent in the pale islands. The tumour cells are focally synaptophysin and chromogranin positive. The topoisomerase index is about 20%. INI1 and NeuN are negative.

B-catenin is negative. GAB1 and YAP1 are focally positive. p53 is negative in most of the tumour cells.

DIAGNOSIS: Desmoplastic/nodular medulloblastoma, SSH-activated and TP53-wildtype (WHO Grade IV).

Case Discussion

The desmoplastic/nodular SSH medulloblastoma, which this is, tend to occur in the lateral parts of the cerebellar hemispheres and more common in young children (<4 years) and adults (>16 years) with an equal M:F.

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Case information

rID: 56138
Published: 17th Oct 2017
Last edited: 16th Jul 2018
Inclusion in quiz mode: Included

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