Friday, May 27, 2016

Summary of the Major Changes in the 2016 WHO Classification of CNS Tumors

Major restructuring of medulloblastomas, with incorporation of genetically defined entities

Addition of brain invasion as a criterion for atypical meningioma

Restructuring of solitary fibrous tumor and hemangiopericytoma (SFT/HPC) as one entity and adapting a grading system to accommodate this change

Expansion and clarification of entities included in nerve sheath tumors, with addition of hybrid nerve sheath tumors and separation of melanotic schwannoma from other schwannomas

Expansion of entities included in hematopoietic/lymphoid tumors of the CNS (lymphomas and histiocytic tumors)

Addition of the following newly recognized entities, variants and patterns:

- IDH-wildtype and IDH-mutant glioblastoma (entities)

- Diffuse midline glioma, H3 K27M–mutant (entity)

- Embryonal tumour with multilayered rosettes, C19MC-altered (entity)

- Ependymoma, RELA fusion–positive (entity)

- Diffuse leptomeningeal glioneuronal tumor (entity)

- Anaplastic PXA (entity)

- Epithelioid glioblastoma (variant)

- Glioblastoma with primitive neuronal component (pattern)

- Multinodular and vacuolated pattern of ganglion cell tumor (pattern)

Deletion of the following entities, variants and terms:

- Gliomatosis cerebri

- Protoplasmic and fibrillary astrocytoma variants

- Cellular ependymoma variant

- “Primitive neuroectodermal tumour” terminology

(Adapted from table 2 in Louis DN et al. The 2016 World Health Organization Classification of Tumors of the Central Nervous System: a summary. Acta Neuropathol (2016) 131:803–820.

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