Department of Pathology, University of Oklahoma Health Sciences Center

Medulloblastoma

   Click on thumbnails to see enlarged pictures.

• [Click here to see a gross picture.]
• Panel A: Medulloblastoma is typically a densely packed, highly cellular small blue cells neoplasm with small and hyperchromatic nuclei. In contrast to medulloepithelioma, the tumor cells arrange in solid sheets without forming any specific pattern. This pattern is more reminiscent of the early but not earliest stage of embryonal development of the central nervous system.  Occasionally, Homer Wright rossettes can be seen in medulloblastomas. Mitotic activity is very brisk and many apoptotic bodies are also present. 
• Panel B: The cell boundaries between different cells cannot be distinguish in medulloblastoma cells. The cytoplasm often appear slightly fibrillary and they are called neuropils.
• Panel C: The morphologic features of medulloblastomas is that of a small blue cell tumor without significant morphologic details for classification. At the molecular level, expression of markers suggestive of certain lineage of differentiation can be detected by immunohistochemistry. In this photo, the tumor strongly express (brown stain) synaptophysin, a protein that is associated with neuroendocrine differentiation. Medulloblastomas also often express other markers that is associated with neuronal and glial differentiation.

For Comment: KarMing-Fung@ouhsc.edu