Rare form of extraovarian peritoneal serous papillary carcinoma with solitary tumor in the abdominal wall: a case report and literature review.

Cases of cancer presenting with microscopically confirmed metastatic malignancies for which no primary site can be detected are a challenge to stage clinically. Adenocarcinoma of unknown primary site is a subtype with high frequency that has no standard treatment and a poor prognosis. A 32-year-old female was found to have a tumor in the abdominal wall. Tumorectomy was conducted. A pathological examination indicated serous papillary adenocarcinoma, and peritoneal or ovarian cancer was suspected. Exploratory laparotomy and partial resection of the ovaries were carried out, but there were no malignant findings in the peritoneum, ovarian tissue or ascitic fluid. This is an extremely rare case of serous papillary adenocarcinoma with a cystic tumor that was categorized as extraovarian peritoneal serous papillary carcinoma (EPSPC) without other clinical findings.