Malignant mesothelioma of the peritoneum invading the liver and mimicking metastatic carcinoma: a case report.

We present a case of malignant mesothelioma of the peritoneum with massive direct invasion to the liver in a 58-year-old Japanese woman. She had no history of asbestos exposure or other malignancies. Abdominal computed tomography revealed one 8-cm intrahepatic mass adjacent to the abdominal wall with peritoneal thickening, multiple smaller nodules in the peritoneal cavity, and intra-abdominal lymphadenopathy. Liver biopsy showed a small cluster of atypical cells similar to epithelial neoplasm, which formed a tubulopapillary structure. The tumor cells were positive for calretinin with strong nuclear and cytoplasmic expression together with podoplanin (D2-40) and some cytokeratins, but were negative for hepatocyte paraffin 1 and other adenocarcinoma markers. We confirmed a diffuse peritoneal mesothelioma with direct invasion to the liver. Liver masses with other peritoneal nodules are mostly encountered as metastatic diseases. However, the possibility of mesothelioma should be considered, even in women without an apparent history of asbestos exposure.