Huge peritoneal malignant mesothelioma mimicking primary ovarian carcinoma

Peritoneal malignant mesothelioma (PMM) is less commonly found in female than male. The most important differential diagnosis of PMM in female patient is primary ovarian carcinoma because of their similar symptoms e.g. dyspepsia, abdominal discomfort from ascites, palpable abdominal mass, etc. However common clinical presentation of PMM is diffuse spread of peritoneal lesions without dominating tumor mass while primary ovarian tumor usually presents with large pelvic mass and smaller exta-ovarian metastatic lesions. The surgeon may make a provisional intraoperative diagnosis of PMM if both ovaries are clearly identified Unfortunately, both conditions frequently elicit fibrosis and adhesion that the exact location or the origin of tumor cannot be clearly stated. Histopathologic diagnosis of PMM is also difficult because it has three patterns of histopathology as biphasic tumors composed of epithelial and sarcomatous components or it may be monophasic of either type. When only the epithelial component is found, serous ovarian carcinoma is the important differential diagnosis while the biphasic mesothelioma must be differentiated from malignant mesodermal mixed tumor or carcinosarcoma of the ovary. The pathologist generally requires immunohistochemical study to achieve a correct diagnosis. The clinical feature and detailed histopathologic findings of the patient with PMM will be discussed