J Pathol Transl Med.  2024 Nov;58(6):346-349. 10.4132/jptm.2024.09.11.

What’s new in neuropathology 2024: CNS WHO 5th edition updates

• Smith H
• Ahrendsen JT

• KMID: 2560676
• DOI: http://doi.org/10.4132/jptm.2024.09.11

Abstract

The fifth edition of the World Health Organization (WHO) Classification of Central Nervous System (CNS) Tumors was released in 2021, just five years following the updated fourth edition. Advanced molecular testing such as next-generation sequencing, RNA fusion analysis, and DNA methylation profiling has led to more precise grading and classification of pre-existing tumor types as well as the recognition of new ones. Herein, we outline the major updates of the 2021 WHO Classification of CNS tumors, with emphasis on the expanded molecular characterization of CNS tumors.

Figure

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  Fig. 1. Polymorphous low-grade neuroepithelial tumor of the young (PLNTY). Low-grade neoplasm demonstrating diffuse growth pattern and microcalcifications (top panel). Strong, regional CD34 expression by tumor cells (bottom panel).

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  Fig. 2. Myxoid glioneuronal tumor. Small, monomorphic “oligo-like” tumor cells embedded in a prominent myxoid matrix. Molecular characterization of this case revealed a PDGFRA p.K385L mutation.

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  Fig. 3. Primary intracranial sarcoma, DICER1-mutant. Malignant spindle cells arranged in fascicles. Tumor cells in the center with characteristic eosinophilic cytoplasmic globules.

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  Fig. 4. Desmoplastic myxoid tumor of the pineal region, SMARCB1-mutant. Histology (top panel) reveals cords of epithelioid tumor cells embedded in a variably myxoid (shown) and desmoplastic (not shown) stroma. Immunohistochemistry demonstrates loss of nuclear SMARCB1 (INI1) expression in tumor cells (bottom panel).