Histological features of medulloblastoma

Hematoxylin and eosin staining of (A) classic medulloblastoma, with sheets of small round blue cells with scant cytoplasm; (B) desmoplastic medulloblastoma, characterized by nodular areas of densely packed, reticulin-rich cells, which show features of neuronal differentiation when stained with synaptophysin (not shown);
(C) large cell and (D) anaplastic medulloblastoma, with prominent and pleomorphic nuclei with large areas of necrosis and high mitotic rate.

Of note, because nearly all large cell tumors also demonstrate an anaplastic component and both large cell and anaplastic tumors are associated with poor prognosis, large cell/anaplastic variant is a single combined category in the World Health Organization (WHO) classification system ^[1].