Department of Anatomical Pathology, Flinders University and SA Pathology, Adelaide, SA, Australia.
Department of Pathology, Chiba University Hospital, Chiba, Japan.
Pathology. 2021 Jun;53(4):446-453. doi: 10.1016/j.pathol.2020.12.005. Epub 2021 Mar 26.
Diffuse malignant mesothelioma (MM) is an incurable tumour of the serosal membranes, which is often caused by exposure to asbestos and commonly diagnosed at advanced stage. Malignant mesothelioma in situ (MMIS) is now included as diagnostic category by the World Health Organization (WHO). However, our international survey of 34 pulmonary pathologists with an interest in MM diagnosis highlights inconsistency regarding how the diagnosis is being made by experts, despite published guidelines. Whilst the WHO restricts the diagnosis to surgical samples, the very concept has implication for cytological diagnosis, which is already regarded as controversial in itself by some. MMIS is currently only applicable as precursor to MM with an epithelioid component, and raises the possibility for different molecular pathways for different histological MM subtypes. The clinical implications of MMIS at this stage are uncertain, but aggressive therapies are being initiated in some instances. Based on the results of the survey we here present a critical appraisal of the concept, its clinical and conceptual implications and provide practice suggestions for diagnosis. A low threshold for ancillary testing is suggested. The designations of 'malignant mesothelioma, cannot exclude MMIS' or 'atypical mesothelial proliferation with molecular indicators of malignancy, so-called MMIS' could be used on cytology samples, adding 'no evidence of invasion in sample provided' for surgical samples. Clinical and radiological correlation are integral to diagnosis and best done at multidisciplinary meetings. Finally, collaborative studies are required to improve our understanding of MMIS.
弥漫性恶性间皮瘤 (MM) 是一种发生于浆膜的无法治愈的肿瘤，通常由接触石棉引起，并且通常在晚期诊断。恶性间皮瘤原位 (MMIS) 现在被世界卫生组织 (WHO) 纳入诊断类别。然而，我们对 34 位对 MM 诊断感兴趣的肺部病理学家进行的国际调查强调了专家在做出诊断时的不一致性，尽管有已发表的指南。虽然 WHO 将诊断仅限于手术样本，但这一概念对细胞学诊断具有影响，而细胞学诊断本身已经被一些人认为存在争议。MMIS 目前仅适用于具有上皮样成分的 MM 的前体，并提出了不同组织学 MM 亚型的不同分子途径的可能性。在现阶段，MMIS 的临床意义尚不确定，但在某些情况下已经开始采用激进的治疗方法。基于调查结果，我们在此对该概念进行了批判性评估，探讨了其临床和概念意义，并为诊断提供了实践建议。建议对辅助检测采取低门槛。可以在细胞学样本上使用“恶性间皮瘤，不能排除 MMIS”或“具有恶性分子指标的非典型间皮增生，所谓的 MMIS”等诊断，并在手术样本上添加“所提供样本中无浸润证据”。临床和放射学相关性是诊断的重要组成部分，最好在多学科会议上进行。最后，需要开展协作研究以提高我们对 MMIS 的理解。
