[Morphology of secondary ovarian tumors and metastases]

The distinction between primary and secondary (metastatic) ovarian tumors is essential for the selection of appropriate surgical interventions, chemotherapeutic treatment and prognostic evaluation for the patient. Metastatic tumors of the ovary range between 5 % and 30 %. The majority of ovarian metastases in Europe and North America derive from colorectal (25-50 %) and breast cancers (8-25 %). A major issue is the differential diagnosis of mucinous tumors. Major features favoring metastasis include bilaterality, size < 10 cm, ovarian surface involvement, extensive intra-abdominal spread, and infiltrative growth within the ovary involving the corpus albicans and corpora lutea. An algorithm using bilaterality and tumor size (cut-off 10 cm) allows correct categorization in approximately  85 % of the cases. Although immunohistochemistry (especially CK7 and CK20 in mucinous tumors) using a panel of antibodies plays a valuable role and is paramount in the diagnosis, the results must be interpreted with caution and within the relevant clinical and histopathological context. It is necessary to note that the correct diagnosis of ovarian metastases always needs interdisciplinary and multidisciplinary approaches.