Abstract: Objective To investigate the clinical characteristics and causes of misdiagnosis of refractory ascites caused by benign multicystic peritoneal mesothelioma. Methods A case of benign multicystic peritoneal mesothelioma with grade Ⅳ cardiac function was misdiagnosed retrospectively. Results This patient had paroxysmal dyspnea after coronary stenting 5 years ago, aggravated with abdominal distension, and went to the hospital for 3 months. At admission, bilateral pleural effusion accompanied by a large amount of peritoneal effusion. Echocardiography showed "EF value 23%". Other examinations did not indicate other organic and abdominal infectious diseases, and cardiac peritoneal effusion was considered. After receiving anti heart failure treatment, the symptoms did not improve significantly. Further examination revealed polycystic solid lesions in the peritoneum, which was diagnosed as "polycystic mesothelioma of the peritoneum". Due to poor systemic tolerance, the patient did not receive any relevant treatment and died of circulatory failure 2 months after admission. Conclusion The incidence of peritoneal mesothelioma is extremely low, lack of specific symptoms and examination. If refractory ascites can not be explained by the primary disease, the possibility of peritoneal mesothelioma should be alert, so as to avoid misdiagnosis.

Key words: multicystic peritoneal mesothelioma, misdiagnosis, heart failure, ascites