Medulloblastoma
Pronunciation: med-uh-loh-blas-TOH-mah
The most common malignant brain tumour of childhood, arising in the cerebellum and classified by histological variant and molecular subgroup under WHO CNS5.
Full Definition
Medulloblastoma is an embryonal neuroepithelial tumour exclusively found in the cerebellum and predominantly affecting children under 15 years. Histological variants include classic, desmoplastic/nodular, medulloblastoma with extensive nodularity (MBEN), and large cell/anaplastic. The current WHO CNS5 classification also mandates molecular subgrouping into WNT-activated, SHH-activated (TP53-wildtype or TP53-mutant), Group 3, and Group 4, each with distinct prognostic profiles. Editors must ensure that both histological and molecular designations are present in contemporary pathology reports; legacy reports using only histological grades (formerly WHO grade IV) do not meet current documentation standards. The term is often misspelled as 'meduloblastoma' (single 'l').
Usage
Usage note: In reports dated from 2021 onward, include both histological variant and molecular subgroup; the single-'l' misspelling 'meduloblastoma' is a frequent editorial error.
In Context
- "Molecular profiling classified the tumour as WNT-activated medulloblastoma, which is associated with the most favourable prognosis." — Pediatric neuropathology report
- "The draft report listed only the histological variant; the editor flagged the omission of the required molecular subgroup designation." — Quality-assurance review of pathology report