CNS tumor
Diffuse astrocytic and oligodendroglial tumors
Anaplastic astrocytoma, NOS
Author: John DeWitt, M.D., Ph.D.
Editor-in-Chief: Debra L. Zynger, M.D.
Topic Completed: 14 January 2020
Minor changes: 7 May 2021
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: Anaplastic astrocytoma[TI] central nervous system
Table of Contents
Definition / general | Essential features | ICD coding | Grading | Additional references | Board review style question #1 | Board review style answer #1Cite this page: DeWitt J. Anaplastic astrocytoma, NOS. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cnstumoranaplasticastrocytoma.html. Accessed October 23rd, 2021.
Definition / general
- WHO 2016 definition: a tumor with morphological features of anaplastic astrocytoma in which IDH mutation status has not been fully assessed (Louis: WHO Classification of Tumours of the Central Nervous System, 4th Edition, 2016)
Essential features
- The 2016 WHO defines a not otherwise specified (NOS) designation appropriate when diagnostic information (histological or molecular) necessary to assign a more specific WHO designation is not available
- Based on 2016 WHO recommendations, full assessment of IDH mutational status includes sequence analysis of IDH1 codon 132 and IDH2 codon 172 when R132H-IDH1 immunohistochemistry is negative
- Therefore, a histologic anaplastic astrocytoma with a negative R132H-IDH1 stain would be assigned a diagnosis of anaplastic astrocytoma, NOS in the absence of molecular testing for definitive IDH status
- See Anaplastic astrocytoma, IDH-mutant and Anaplastic astrocytoma, IDH-wildtype for further features, imaging, microscopic, etc
ICD coding
- ICD-10: C71.9 - malignant neoplasm of brain, unspecified
Grading
- Grade III of IV
Additional references
Board review style question #1
- You are working up a diffusely infiltrating astrocytic glial tumor that shows mitotic activity and pleomorphism but no evidence of necrosis or microvascular proliferation. Immunohistochemical work up reveals tumor cells are negative for R132H-IDH1 and retain ATRX. What is the proper diagnosis given the available information?
- Anaplastic astrocytoma, IDH-wildtype
- Diffuse astrocytoma, IDH-wildtype
- Glioblastoma, IDH-wildtype
- Anaplastic astrocytoma, NOS
- Diffuse astrocytoma, NOS
Board review style answer #1
