Original ArticleThe Mitosis-Specific Antibody Anti-Phosphohistone-H3 (PHH3) Facilitates Rapid Reliable Grading of Meningiomas According to WHO 2000 CriteriaRibalta, Teresa MD, PHD*; McCutcheon, Ian E MD‡; Aldape, Kenneth D MD, PHD†; Bruner, Janet M MD†; Fuller, Gregory N MD, PHD†Author Information From the Departments of †Pathology and ‡Neurosurgery, University of Texas M. D. Anderson Cancer Center, Houston, TX; and the *Department of Pathology, Hospital Clinic, Institut d’Investigacions Biomèdiques August Pi i Suñer, Universitat de Barcelona, Barcelona, Spain. Preliminary results of this study were presented at the United States and Canadian Academy of Pathology 91st Annual Meeting, Chicago, IL, February 23–March 2, 2002. Reprints: Gregory N. Fuller, MD, PhD, M. D. Anderson Cancer Center, Department of Pathology (Neuropathology), 1515 Holcombe Blvd., Houston, TX 77030 (e-mail: email@example.com). The American Journal of Surgical Pathology: November 2004 - Volume 28 - Issue 11 - p 1532-1536 doi: 10.1097/01.pas.0000141389.06925.d5 Buy SDC Metrics Abstract Mitotic figure (MF) counting is the most objective criterion for grading of meningiomas according to the 2000 World Health Organization (WHO) classification. However, the search for the area(s) of highest mitotic activity is tedious, and there is high interobserver variability in differentiating MF from apoptotic cells. We tested the utility of the mitosis-specific marker phosphohistone-H3 (PHH3) to enhance rapid recognition of MFs and quick reliable grading of meningioma. Fifty-four archival meningiomas (26 benign, 20 atypical, 8 anaplastic) were reclassified according to current WHO criteria. PHH3-immunostained MFs were counted the same way as in hematoxylin and eosin-stained sections. Anti-PHH3-labeled MFs were easily seen and permitted quick identification of the area(s) of highest mitotic activity. Count results (mean) show a strong correlation between both methods: benign, hematoxylin and eosin 1.4, PHH3 2.2; atypical, hematoxylin and eosin 9.0, PHH3 15.9; anaplastic, hematoxylin and eosin 22.4, PHH3 34.1. PHH3 counting yielded greater sensitivity and in 12 cases (22.2%) suggested a change in grade (increased 9; lowered 3). All cases in which PHH3 lowered the grade were from older blocks, suggesting a loss of antigen preservation. PHH3 immunostaining facilitates the rapid reliable grading of meningiomas by focusing attention on the most mitotically active areas and by allowing easy and objective differentiation of MFs from apoptotic nuclei. © 2004 Lippincott Williams & Wilkins, Inc.