Isolated Ovarian Metastasis from Pancreatic Cancer Mimicking Primary Ovarian Neoplasia: Role of Molecular Analysis in Determining Diagnosis.

Background and Presentation: In this study, we present the case of a 64-year-old female with a chief complaint of abdominal pain and bloating, which had been persistent over a period of 4 months. Imaging revealed a 6.1-cm left-sided pancreatic mass as well as a 19.1-cm multiloculated cystic lesion in the pelvis, later revealed to be replacing the left ovary. The pancreatic mass was biopsied through endoscopic ultrasound-guided fine needle aspiration, and diagnosed as adenocarcinoma by cytology. The patient was treated with neoadjuvant chemotherapy and radiation before laparotomy for resection of the pancreas and left adnexal mass. Her response to treatment was followed radiologically and biochemically with cancer antigen (CA) 19-9 (114-35 U/mL), carcinoembryonic antigen (12-4.8 ng/mL), and CA-125 (119-15.3 U/mL) levels. She subsequently underwent an Appleby procedure, and resection of left pelvic mass and bilateral oophorectomy. Permanent sections revealed residual pancreatic ductal carcinoma with treatment effect, and a multicystic epithelial neoplasia of the left ovary for which the differential was primary ovarian carcinoma versus metastatic disease. Conclusions: Molecular mutational analysis was performed on sections of both the ovarian tumor and the pancreatic tumor to aid in diagnosis. The ovarian tumor in this case showed exactly the same mutations, KRAS G12R and TP53 G245S, as in the treated pancreatic cancer. This raised the high probability that these tumors originated from the same clonal event. The findings suggested that the ovarian tumor was an isolated metastasis of the pancreatic primary, despite the morphologic ambiguity between the two sites of neoplasia.