Abstract
Diffuse malignant peritoneal mesothelioma (DMPM) and peritoneal carcinomatosis have similar computed tomography imaging features. Peritoneal carcinomatosis is a known metastatic site for many malignancies and particularly gastrointestinal tract and ovarian cancers. Also, DMPM can masquerade as an ovarian epithelial neoplasm, with very similar clinical presentation and an overlap in imaging findings. When no evident primary tumor is detected other than the peritoneal disease, primary malignant mesothelioma should be considered. Since accurate diagnosis is essential for treatment management, the gold standard in differentiating between these two entities lies in histological analysis. We report a case of DMPM that was initially misdiagnosed as an ovarian cancer, where the biopsy of a peritoneal nodule was able to correct and confirm the diagnosis of DMPM.