A Case of Malignant Peritoneal Mesothelioma Treated with Cisplatin and Pemetrexed

: A 65-year-old man was admitted to our hospital complaining of general malaise, anorexia and weight loss. A computed tomography(CT)scan showed massive ascites and multiple peritoneal masses. Although adenocarcinoma was suspected based on the cytology of the ascites, we were unable to determine the site of origin. We next performed a laparoscopy and a biopsy of the tumor on the omentum. The laparoscopy showed small, white, hard nodules that were disseminated throughout the abdominalcavity, and histologicaldiagnosis confirmed malignant peritonealmesothel ioma. The patient was administered chemotherapeutic treatment of cisplatin and pemetrexed. After treatment, the ascites decreased; however, tumor regression was not observed. The patient's performance status gradually decreased, and he died on hospital day 104. Prognosis of malignant peritoneal mesothelioma remains poor, and malignant peritoneal mesothelioma should be considered when diagnosing peritoneal tumors.