The role of imaging in diagnosis and management of malignant peritoneal mesothelioma: a systematic review

Mesotheliomas and Benign Mesothelial Tumors: Update on Pathologic and Imaging Findings

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.

A case of malignant peritoneal mesothelioma with a Fitz-Hugh-Curtis syndrome-like imaging finding

Malignant peritoneal mesothelioma (MPeM) is a rare disease with a poor prognosis that develops in the mesothelial cells of the peritoneum. We encountered a 48-year-old man with no prior asbestos exposure who visited our hospital with abdominal pain. Laboratory findings showed elevated C-reactive protein of 15.5 mg/dL. Contrast-enhanced computed tomography (CT) detected a Fitz-Hugh-Curtis syndrome-like contrast effect on the liver surface and thickening of the peritoneum. Blood culture, Mycobacterium tuberculosis-specific IFN-γ release assay, Chlamydia trachomatis and Neisseria gonorrhoeae DNA testing, and antinuclear antibody were all negative. CA125 was high at 124.8 U/mL. The laparoscopy for diagnostic purposes revealed adhesions between the liver surface and peritoneum in addition to numerous small and large white nodules on the peritoneum. Biopsy of the nodules confirmed the diagnosis of epithelial-type MPeM. Treatment was initiated with combined cisplatin and pemetrexed, and CT 6 months later showed a reduced contrast effect on the liver surface and improved peritoneal thickening. A Fitz-Hugh-Curtis syndrome-like contrast effect on the liver surface on contrast-enhanced CT may help identify MPeM.

FDG PET/CT for Staging and Restaging Malignant Mesothelioma

Malignant mesothelioma is an aggressive tumor originating from the mesothelial cells and presenting in general with a very poor prognosis. The pleural localization represents the prevailing disease site, while peritoneal involvement is commonly rare. The WHO classifies mesotheliomas into epithelioid, biphasic, and sarcomatoid histotypes, having diverse outcome with the sarcomatoid or biphasic forms showing the poorest prognosis. Given the peculiar rind-like pattern of growth, mesothelioma assessment is rather challenging for medical imagers. Conventional imaging is principally based on contrast-enhanced CT, while the role of functional and metabolic imaging is regarded as complementary. By focusing essentially on the staging and restaging role of [18F]FDG PET/CT in malignant mesotheliomas, the present review will summarize the available data present in literature and provide some hints on alternative imaging and future perspectives. Given the prevailing incidence of pleural disease, the majority of the information will be addressed on malignant pleural mesothelioma, although a summary of principal characteristics and imaging findings in patients with peritoneal mesothelioma will be also provided.