Updates on WHO classification for small round cell tumors: Ewing sarcoma vs. everything else

Carina A Dehner; Alexander J Lazar; John S A Chrisinger

doi:10.1016/j.humpath.2024.01.007

Updates on WHO classification for small round cell tumors: Ewing sarcoma vs. everything else

Hum Pathol. 2024 Jan 26:S0046-8177(24)00007-8. doi: 10.1016/j.humpath.2024.01.007. Online ahead of print.

Authors

Carina A Dehner¹, Alexander J Lazar², John S A Chrisinger³

Affiliations

¹ Department of Anatomic Pathology and Laboratory Medicine, Indiana University, 635 Barnhill Drive, Indianapolis, IN, 46202, USA. Electronic address: cadehner@iu.edu.
² Department of Pathology, University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX, 77030, USA; Department of Genomic Medicine, University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX, 77030, USA. Electronic address: alazar@mdanderson.org.
³ Department of Pathology and Immunology, Division of Anatomic and Molecular Pathology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA. Electronic address: jschrisi@wustl.edu.

PMID: 38280658
DOI: 10.1016/j.humpath.2024.01.007

Abstract

The WHO Classification of Soft Tissue and Bone Tumours currently recognizes four categories of undifferentiated small round cell sarcoma: Ewing sarcoma, round cell sarcoma with EWSR1-non-ETS fusions including NFATc2 and PATZ1, CIC-rearranged sarcoma, and sarcoma with BCOR genetic alterations. These neoplasms frequently pose significant diagnostic challenges due to rarity and overlapping morphologic and immunohistochemical findings. Further, molecular testing, with accompanying pitfalls, may be needed to establish a definitive diagnosis. This review summarizes the clinical, histologic, immunohistochemical, and molecular features of these neoplasms. In addition, differential diagnosis and areas of uncertainty and ongoing investigation are discussed.

Keywords: BCOR; CIC; Ewing sarcoma; Ewing-like; NFATc2; PATZ1; Review; Round cell.

Publication types

Review