Malignant pleural mesothelioma (MPM) is a rare aggressive tumor arising from the mesothelial layer of the pleura and related prevalently to the exposure of asbestos fibers.1,2 It represents mostly a deadly diagnosis, leading to over 38,000 cancer-related deaths worldwide.3,4 Given its peculiar pattern of growth throughout the pleural lining, MPM can represent both a clinical and an imaging challenge, due to the frequency of subtle symptoms not directly attributable to a malignant disease, and to the exiguity of tumor lesions at early disease stages.3 Depending on the gravity of the disease, manifestations can vary from pleural effusion (up to 95% of the cases), to chest pain, short breath, dysphagia, or more debilitating consequences. The World Health Organization (WHO) TNM classification of mesothelioma defines the tumor stage,5 which determines the management of MPM varying from surgical intervention to a combination of systemic chemotherapy, immunotherapy, and radiation therapy.6 In 2021 it also introduced significant modifications compared to earlier classifications, by renaming well-differentiated papillary mesothelioma (WDPM) as well-differentiated papillary mesothelial tumor (WDPMT) to reflect its relatively indolent nature,7 and by recognizing mesothelioma in situ as a distinct pathological entity,7,8 The classification also integrates architectural, cytological, and stromal characteristics from the 3 established histological types—epithelioid, sarcomatoid, and biphasic—due to their prognostic significance, as well as nuclear grading for epithelioid diffuse mesothelioma.9

Major International scientific societies, such as the International Mesothelioma Interest Group (IMIG), the International Association for the Study of Lung (IASL),10, 11, 12 the European Society for Medical Oncology (ESMO)13, the National Comprehensive Cancer Network (NCCN),14 European Respiratory Society (ERS)/European Society of Thoracic Surgeons (ESTS)/European Association for Cardio-Thoracic Surgery (EACTS)/European Society for Radiotherapy and Oncology (ESTRO) (ERS/ESTS/EACTS/ESTRO)15 have provided continuous updates on proper handling of MPM patients, including recommendations on the optimal imaging algorithms, which are crucial for determining effective treatment options and optimizing clinical outcomes. Alongside the current WHO TNM Classification (Fig. 1), the IASL Cancer Pleural Mesothelioma Staging Project has recently proposed new revisions of the TNM stage groupings to be embedded in the forthcoming (Ninth) Edition of the TNM Classification for Pleural Mesothelioma (Table 1).16, 17, 18 However, despite the continuous efforts to improve patients’ prognosis, median overall survival remains poor, ranging from 8 to 14 months.4 And even in case of initial response to treatment, local or distant recurrences represent almost a certainty, requiring appropriate imaging for the assessment of tumor sites.19

The aim of the present article is to illustrate the current status of imaging for staging and restaging of MPM, not forgetting most recent novelties in the diagnostic work-up of the disease.