Primary peritoneal carcinoma
Primary peritoneal cancer or carcinoma is also known as serous surface papillary carcinoma, primary peritoneal carcinoma, extra-ovarian serous carcinoma, primary serous papillary carcinoma, and psammomacarcinoma. It was historically classified under "carcinoma of unknown primary" (CUP).
Source: Wikipedia — Primary peritoneal carcinoma (CC BY-SA 4.0)