Malignant Peritoneal Mesothelioma Features Shown by FDG-PET/CT

Background/aim: Malignant peritoneal meso-thelioma (MPeM) has no specific imaging findings that can distinguish it from other peritoneal tumors and the accuracy of peritoneal cytology is low, therefore definitive diagnosis is usually performed by histology. This study investigated whether ¹⁸ F-fluorodeoxyglucose positron emission tomography/ computed tomography representing glucose metabolism is a useful modality for identifying biopsy sites using the tumor viability of MPeM.

Patients and methods: Sixty MPeM patients underwent pre-biopsy FDG-PET/CT examination. The findings were retrospectively evaluated, and histopathological subtype differences were investigated.

Results: The diffuse MPeM type was found in 45 (75.0%) and the localized type in 15 (25.0%) cases. The most frequent site of occurrence was the peritoneum (91.7%), followed by the omentum (51.7%). FDG-avid results were noted in 55 patients (91.7%), while 5 (8.3%) showed no FDG uptake with a variety of maximum standardize uptake value (SUV_max) values (range=0-16.77, mean=7.32±4.05). In the 53 epithelial cases, mean SUV_max (7.09±4.07, range=0-16.77) was slightly lower compared to the 4 biphasic (8.30±4.70, range=2.35-13.36) and 3 sarcomatoid (10.08±2.64, range=8.21-13.10) cases, without any significant difference (p=0.12). Diffuse and focal disease patterns showed similar percentages in the three types. Six cases (10.0%) had nodal metastases and 6 (10.0%) extra-abdominal metastases. Compared to the biphasic and sarcomatoid groups, nodal metastases were more common in the epithelial group, while extra-abdominal metastases were more often seen in the biphasic and sarcomatoid groups. Ascites was seen in 53 (83.3%), pleural effusion in 43 (71.7%), and pleural plaque in 31 (51.7%) cases.

Conclusion: Through reviewing and elucidation of the FDG-PET/CT features of MPeM, it was shown that FDG-PET/CT is an extremely useful modality for identifying biopsy sites of MPeM.