多种良性实体和恶性新生物起源于排列在胸膜、心包和腹膜腔的浆膜膜的单调中皮层。多种部位的中皮层都表现出来自侧板中胚层的共同起源；因此，原发性中皮瘤表现出相似的发病机制、成像结果和治疗选项。根据病理学和遗传学的最新进展，2021年世界卫生组织（WHO）的胸膜和心包肿瘤分类方案进行了重大变革。虽然恶性间皮瘤是生物学上具有侵袭性的恶性肿瘤，主要发生在暴露于石棉的患者中，并伴有较差的生存率，但良性不良分化乳头状中皮瘤和腺瘤样肿瘤则具有良好的临床预后。间皮样癌是一种新近描述的实体，代表了反复发作的不明原因的胸膜积液，成像或胸腔镜检查时没有发现任何肿块。基于BAP1、MTAP、CDKN2A和TRAF7基因突变的免疫组化标记有助于区分弥漫性间皮瘤和良性中皮增生和局限性间皮瘤。包括超声、CT、MRI和氟-18-脱氧葡萄糖（FDG）PET / CT在内的断层成像技术可以诊断并在分期和评估手术可行性方面起到重要作用。影像研究在为无法手术切除的患者提供肿瘤反应的非侵入性和定量评估方面具有不可估量的作用。由于患者特征和病理形态重叠显著，因此基于先进的组织病理学技术和基因异常的准确诊断对于最佳管理和预后至关重要。虽然非上皮胸膜间皮瘤的患者受益于免疫治疗，但CDKN2A、NF2和BAP1突变的新型靶向治疗正在考虑中。©RSNA，2023本文的问答题可通过在线学习中心获得。

A diverse spectrum of benign entities and malignant neoplasms originate from the monotonous mesothelium that lines the serosal membranes of the pleural, pericardial, and peritoneal cavities. The mesothelium of myriad sites shows a common origin from the lateral plate mesoderm; primary mesothelial tumors thus demonstrate similar pathogenesis, imaging findings, and treatment options. Significant changes have been made in the 2021 World Health Organization (WHO) classification schemata of the pleural and pericardial tumors on the basis of recent advances in pathology and genetics. While malignant mesotheliomas are biologically aggressive malignancies that occur primarily in patients exposed to asbestos with attendant poor survival rates, well-differentiated papillary mesothelial tumors and adenomatoid tumors charter a benign clinical course with an excellent prognosis. Mesothelioma in situ is a newly characterized entity represented by recurrent unexplained pleural effusions without any identifiable mass at imaging or thoracoscopy. Immunohistochemical markers based on BAP1, MTAP, CDKN2A, and TRAF7 gene mutations help differentiate diffuse mesotheliomas from benign mesothelial proliferations and localized mesotheliomas. Cross-sectional imaging modalities, including US, CT, MRI, and fluorine 18-fluorodeoxyglucose (FDG) PET/CT, permit diagnosis and play a major role in staging and assessing surgical resectability. Imaging studies are invaluable in providing noninvasive and quantitative assessment of tumor response in patients with unresectable disease. Owing to significant overlap in patient characteristics and pathomorphology, accurate diagnosis based on advanced histopathology techniques and genetic abnormalities is imperative for optimal management and prognostication. While patients with nonepithelioid pleural mesotheliomas benefit from immunotherapy, novel targeted therapies for CDKN2A-, NF2-, and BAP1-altered mesotheliomas are under consideration. © RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.