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Marx A, Chan JKC, Chalabreysse L, Dacic S, Detterbeck F, French CA, Hornick JL, Inagaki H, Jain D, Lazar AJ, Marino M, Marom EM, Moreira AL, Nicholson AG, Noguchi M, Nonaka D, Papotti MG, Porubsky S, Sholl LM, Tateyama H, Thomas de Montpréville V, Travis WD, Rajan A, Roden AC, Ströbel P. The 2021 WHO Classification of Tumors of the Thymus and Mediastinum: What Is New in Thymic Epithelial, Germ Cell, and Mesenchymal Tumors? J Thorac Oncol 2021; 17:200-213. [PMID: 34695605 DOI: 10.1016/j.jtho.2021.10.010] [Citation(s) in RCA: 101] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 10/06/2021] [Accepted: 10/07/2021] [Indexed: 01/12/2023]
Abstract
This overview of the fifth edition of the WHO classification of thymic epithelial tumors (including thymomas, thymic carcinomas, and thymic neuroendocrine tumors [NETs]), mediastinal germ cell tumors, and mesenchymal neoplasms aims to (1) list established and new tumor entities and subtypes and (2) focus on diagnostic, molecular, and conceptual advances since publication of the fourth edition in 2015. Diagnostic advances are best exemplified by the immunohistochemical characterization of adenocarcinomas and the recognition of genetic translocations in metaplastic thymomas, rare B2 and B3 thymomas, and hyalinizing clear cell carcinomas. Advancements at the molecular and tumor biological levels of utmost oncological relevance are the findings that thymomas and most thymic carcinomas lack currently targetable mutations, have an extraordinarily low tumor mutational burden, but typically have a programmed death-ligand 1high phenotype. Finally, data underpinning a conceptual advance are illustrated for the future classification of thymic NETs that may fit into the classification scheme of extrathoracic NETs. Endowed with updated clinical information and state-of-the-art positron emission tomography and computed tomography images, the fifth edition of the WHO classification of thymic epithelial tumors, germ cell tumors, and mesenchymal neoplasms with its wealth of new diagnostic and molecular insights will be a valuable source for pathologists, radiologists, surgeons, and oncologists alike. Therapeutic perspectives and research challenges will be addressed as well.
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Affiliation(s)
- Alexander Marx
- Institute of Pathology, University Medical Centre Mannheim, Heidelberg University, Mannheim, Germany.
| | - John K C Chan
- Department of Pathology, Queen Elizabeth Hospital, Kowloon, Hong Kong SAR, People's Republic of China
| | - Lara Chalabreysse
- Department of Pathology, Groupement Hospitalier Est, Bron Cedex Lyon, France
| | - Sanja Dacic
- Department of Pathology, University Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Frank Detterbeck
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Christopher A French
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Jason L Hornick
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Hiroshi Inagaki
- Department of Pathology and Molecular Diagnostics, Nagoya City University, Nagoya, Japan
| | - Deepali Jain
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Alexander J Lazar
- Department of Pathology and Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Mirella Marino
- Department of Pathology, Istituto di Ricovero e Cura a Carattere Scientifico Regina Elena National Cancer Institute, Rome, Italy
| | - Edith M Marom
- Department of Diagnostic Imaging, Chaim Sheba Medical Center, affiliated with Tel Aviv University, Ramat Gan, Israel
| | - Andre L Moreira
- Department of Pathology, New York University Langone Health, New York, New York
| | - Andrew G Nicholson
- Department of Histopathology, Royal Brompton and Harefield Hospitals and National Heart and Lung Institute, Imperial College, London, United Kingdom
| | - Masayuki Noguchi
- Department of Diagnostic Pathology, University of Tsukuba, Tsukuba-shi, Japan
| | - Daisuke Nonaka
- Department of Cellular Pathology, Guy's and St Thomas' NHS Foundation Trust, St Thomas' Hospital, London, United Kingdom
| | | | - Stefan Porubsky
- Department of Pathology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Lynette M Sholl
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
| | - Hisashi Tateyama
- Department of Pathology, Kasugai Municipal Hospital, Kasugai, Japan
| | | | - William D Travis
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Arun Rajan
- Thoracic and Gastrointestinal Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Anja C Roden
- Department of Laboratory Medicine and Pathology, Mayo Clinic Rochester, Rochester, Minnesota
| | - Philipp Ströbel
- Institute of Pathology, University Medical Center Göttingen, Göttingen, Germany
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