Primary malignant mesothelioma of the peritoneum: a clinical and immunohistochemical study

Abstract Background Primary peritoneal mesothelioma is regarded as a fatal disease that presents with progressive ascites at a relatively late stage of its natural history. Differential diagnosis between this rare tumor and both serous papillary carcinoma of the peritoneum and ovary can be problematic. Case A 54-year-old woman presented to our institution with a 4-month history of dull epigastric pain and increased abdominal girth. Exploratory laparotomy revealed the presence of extensive intraperitoneal dissemination of a malignant neoplasm without a recognizable primary site. Suboptimal cytoreduction was carried out, and histological diagnosis was that of a malignant epithelioid mesothelioma. This was confirmed with a panel of immunohistochemical markers. The patient despite having a complete response after adjuvant chemotherapy died 18 months after primary surgery. Conclusion No single immunohistochemical stain is pathognomonic of peritoneal primary malignant mesothelioma (PMM), and the results of a panel of antibodies should be interpreted to set the diagnosis.