If cerebellar= medulloblastoma. If supratentorial= PNET


Suggested by MRI and confirmed by pathology (brain biopsy/resection)

Findings on Investigations:


  • If cerebellar= medulloblastoma. If supratentorial= PNET
  • Medulloblastoma: midline cerebellar, may occur in cerebellar hemispheres, grow into 4th ventricle with distortion of the ventricles shape, uncommonly calcify, cysts are uncommon. Minimal oedema. Moderate enhancement.
  • PNET: supratentorial (frontal, parietal, occipital lobes), large, homogenous, well circumscribed. Enhance heterogeneously. Calcifications, cysts & hemorrhage are common. Minimal oedema.
  • T1, hypointense
  • T2, intermediate intensity, isointense,
  • FLAIR, hyperintense tumor, hyperintensities in subarachnoid space= seeding, with gadolinium it’s more sensitive to seeding, seeding can occur anywhere along the craniospinal axis.
  • TI with contrast: Leptomeningeal enhancement indicates CSF seeding

CT: homogenous, hyperdense, well circumscribed,


Small round blue cells. Homer Wright rosettes.
Desmoplastic medulloblastoma nests of cells arranged in nodules (surrounded by fibrous bands). Medulloepitheliomas= cells arranged in cords or papillae.
Immunohistochemistry: positive for synaptophysin, Trk, nerve growth factor. Variable positivity for NSE, GFA, vimentin, S100


Treatment modalities:

  • Surgery
  • Radiotherapy (craniospinal)
  • Chemotherapy

Related articles: