A Case of Localized Malignant Peritoneal Mesothelioma Evaluated by 18F-FDG PET/CT

18F-FDG PET/CT in Primary Mesothelioma of the Liver

ABSTRACT

Primary malignant mesothelioma is a rarity among malignant liver tumors. We present the case of a 48-year-old woman presenting with increasing upper abdominal discomfort and inappetence accompanied by a weight loss of approximately 10 kg. CT and MRI revealed a highly suspicious mass lesion in the liver. 18F-FDG PET/CT performed for staging showed a pathological 18F-FDG uptake of the known liver tumor. Histology and immunohistochemistry indicated mesothelioma of the liver. Herein we present a rare case of primary mesothelioma in the liver with CT, MRI, and 18F-FDG PET/CT.

Localized Malignant Peritoneal Mesothelioma (LMPeM) in Women: A Clinicopathologic Study of 18 Cases

Localized malignant peritoneal mesothelioma is a rare tumor with limited information in the literature. In this study, we present our experience with 18 cases seen in our hospital over a period of 43 years (1978 to 2021). Patients' median age was 55 years (y) (range: 33 to 79 y) and most of them were Caucasians. Patients presented with abdominal pain (11), ascites and right leg swelling (1), abdominal mass (1), and as incidental finding (1). Thirty percent of patients reported asbestos exposure, and all patients with available information had family history of tumors; a third had personal history of tumors. Seventy-seven percent had some form of abdominopelvic surgery and/or inflammatory process. Most cases had microscopic features typically seen in malignant mesothelioma; however, some cases had confounding features such as signet-ring cells, spindle cells, clear cell changes, and adenomatoid tumor-like appearance. BAP-1 by immunohistochemistry was lost in 1/3 cases. Only 1 patient underwent genetic testing and had an MSH2 germline mutation. Homozygous deletion of CDKN2A by FISH was not found in 1 tested case, although next-generation sequencing identified a CDKN2A pathogenic mutation. 16/18 (88%) had surgical treatment, and some also received adjuvant chemotherapy. The mean overall survival (OS) of our patients was 80.4 months (95% confidence interval: 54.3-106.52); the 3-year OS was 79%, while the 5-year OS was 52.6%. Fifty-three percent of patients had recurrences and 20% had tumor progression. Although the limited sample precludes definitive conclusions, small tumor size, low-grade cytology, and low mitotic index appeared to be associated with an indolent behavior.