[Metastatic tumors in the ovary, difficulties of histologic diagnosis]

The ovary is a common site of metastases. Secondary tumors account for 3-40% of all ovarian malignancies. Most ovarian metastases arise from the colon, although tumors of the breast, stomach and endometrium are also common places of origin. Clinical and histological features of metastatic tumors frequently mimic primary ovarian malignancies, causing serious diagnostic problems for the surgical pathologist. However, differentiation between primary ovarian cancer and ovarian metastasis is important in order to prevent inappropriate management and suboptimal treatment. The distinction between primary and secondary ovarian malignancies is especially difficult in cases when the metastasis is diagnosed before the primary tumor. Frozen section is widely used in the intra-operative assessment of patients with ovarian tumors but it can be very difficult to distinguish certain types of primary ovarian tumors and metastases from other sites. We examined 152 cases of secondary ovarian neoplasm diagnosed at the National Institute of Oncology, Hungary from 2000 to 2014. Colorectal cancer was the most common primary tumor (58 cases), followed by breast (33 cases), endometrium (30 cases) and stomach cancer (13 cases). The differential diagnosis proved the most difficult in cases when endometrioid and mucinous tumors were present in the ovaries. Metastases of colorectal and gastric adenocarcinomas may simulate benign or borderline cystadenomas too. In these cases the knowledge of the patient's history and immunohistochemical stains were helpful. In our study we discuss the diagnostic challenge of distinguishing these secondary ovarian tumors from primary ovarian neoplasms and the limits of the intraoperative frozen sections.