Objective: To evaluate the frequency of metastatic tumors among malignant ovarian neoplasms, the site distribution of the primary malignancies that give rise to ovarian metastasis and the clinicopathologic features of metastatic tumors.

Methods: We analyzed a total number of 116 patients diagnosed with metastasis to the ovary between 1985 and 2007 at the Radboud University Nijmegen Medical Centre. The medical records of the patients were reviewed for age at diagnosis, medical history, menopausal state, clinical manifestation, primary tumor, intraoperative findings, and prognosis. The pathology reports were reviewed for macroscopic appearances and histopathologic features.

Results: Metastasis to the ovary accounted for 15% of all ovarian malignancies identified in the 22-year period at the Radboud University Nijmegen Medical Centre. The gastrointestinal tract was the most common primary site (39%), followed by breast (28%) and endometrium (20%). There were 22 metastases to the ovary that mimicked a primary ovarian tumor at first clinical presentation, of which the single greatest number of cases (36%) originated from a primary tumor of the large intestine. Ovarian cysts were present in 71% of patients, and most ovaries with metastatic disease were 10 cm in diameter or less. Bilateral ovarian involvement was present in 69% of the patients, including all patients with tumors of the stomach.

Conclusion: In case of an ovarian tumor, metastatic disease should always be considered to avoid pitfalls in diagnosis and therapy. The gastrointestinal tract is the most likely location of the primary tumor, followed by breast and endometrium.