Abstract

Diagnostic imaging and workup of malignant pleural mesothelioma

Author(s): Edoardo Piacibello

Malignant pleural mesothelioma (MPM) is the most frequent primary neoplasm of the pleura. Although asbestos use has been banned in many developed countries, the incidence has been significantly increasing because of widespread occupational exposure over the last decades. Since the latency between first asbestos exposure and tumor development is around 40 years, the peak age incidence ranges from the sixth to the eighth decades and, since most asbestos exposure is work-related, the incidence is markedly higher in men than in women, the annual rates being 15 cases per million and 3 cases per million, respectively, in the United States. Most commonly, MPM originates within the parietal pleura located in the lower hemithorax and the costophrenic angle. It spreads locally to the ipsilateral visceral pleura and relentlessly invades adjacent structures, such as the lung, chest wall, diaphragm, pericardium, and mediastinum. Disease may invade the contralateral pleural space and the peritoneum. Lymphatic and hematogenous metastases tend to occur late in natural history but are present at autopsy in approximately 50% of patients with MPM. The clinical manifestations are nonspecific and many patients present with advanced-stage disease and comorbidities. The patient prognosis is poor, with a median survival after diagnosis of approximately 12 months. The diagnosis of this neoplasm is often made at a late stage and the prognosis is still very poor with a median survival from diagnosis of under a year with supportive care alone. Achieving early diagnosis and helping to select the most appropriate treatment option in MPM patients is mandatory. In this pictorial essay, the spectrum of imaging features of MPM at Chest Radiography (CXR), Computed Tomography (CT), Magnetic Resonance (MR), Positron Emission Tomography (PET), integrated PET/CT, and Ultrasonography (US) are discussed, and a diagnostic pathway in patients with undiagnosed pleural effusion is proposed.