<scp>I</scp>nternational <scp>S</scp>ociety of <scp>N</scp>europathology‐<scp>H</scp>aarlem <scp>C</scp>onsensus <scp>G</scp>uidelines for <scp>N</scp>ervous <scp>S</scp>ystem <scp>T</scp>umor <scp>C</scp>lassification and <scp>G</scp>rading

Abstract

Abstract Major discoveries in the biology of nervous system tumors have raised the question of how non‐histological data such as molecular information can be incorporated into the next W orld H ealth O rganization ( WHO ) classification of central nervous system tumors. To address this question, a meeting of neuropathologists with expertise in molecular diagnosis was held in H aarlem, the N etherlands, under the sponsorship of the I nternational S ociety of N europathology ( ISN ). Prior to the meeting, participants solicited input from clinical colleagues in diverse neuro‐oncological specialties. The present “white paper” catalogs the recommendations of the meeting, at which a consensus was reached that incorporation of molecular information into the next WHO classification should follow a set of provided “ ISN ‐ H aarlem” guidelines. Salient recommendations include that (i) diagnostic entities should be defined as narrowly as possible to optimize interobserver reproducibility, clinicopathological predictions and therapeutic planning; (ii) diagnoses should be “layered” with histologic classification, WHO grade and molecular information listed below an “integrated diagnosis”; (iii) determinations should be made for each tumor entity as to whether molecular information is required, suggested or not needed for its definition; (iv) some pediatric entities should be separated from their adult counterparts; (v) input for guiding decisions regarding tumor classification should be solicited from experts in complementary disciplines of neuro‐oncology; and (iv) entity‐specific molecular testing and reporting formats should be followed in diagnostic reports. It is hoped that these guidelines will facilitate the forthcoming update of the fourth edition of the WHO classification of central nervous system tumors.

Keywords

Affiliated Institutions

• Harvard University US
• University Hospital Heidelberg DE
• Johns Hopkins Medicine US
• University of Zurich CH
• University of Virginia US
• University of Cambridge GB
• University Hospital Münster DE
• Aix-Marseille Université FR
• Centre international de recherche sur le cancer FR
• Emory University US
• University of Toronto CA
• University of Bonn DE
• The University of Texas MD Anderson Cancer Center US
• SickKids Foundation CA
• St. Jude Children's Research Hospital US
• Princess Margaret Cancer Centre CA
• Erasmus MC NL
• Hospital for Sick Children CA
• Massachusetts General Hospital US
• Heinrich Heine University Düsseldorf DE
• German Cancer Research Center DE
• University Hospital of Zurich CH
• Sapienza University of Rome IT
• Chinese University of Hong Kong HK
• Amsterdam UMC Location Vrije Universiteit Amsterdam NL
• Johns Hopkins University US
• University of California, San Francisco US
• Hacettepe University TR
• Radboud University Medical Center NL
• Memorial Sloan Kettering Cancer Center US
• Mayo Clinic in Arizona US
• Heidelberg University DE
• Istituto Neurologico Mediterraneo IT
• Radboud University Nijmegen NL

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