Krukenberg tumor

Krukenberg tumors are secondary (metastatic) ovarian neoplasms, most frequently arising from primary gastric adenocarcinoma (especially the diffuse/signet ring cell type per Lauren classification), though colon, appendix, and breast cancers can also seed the ovaries. Spread occurs via lymphatic, hematogenous, or transcoelomic (peritoneal) routes. Bilateral ovarian involvement is characteristic and helps distinguish it from primary ovarian tumors, which are more often unilateral. Grossly, the ovaries are enlarged, solid, and often retain a smooth capsular surface. Microscopically, the hallmark finding is mucin-laden signet ring cells infiltrating the ovarian stroma, which shows a characteristic sarcoma-like (fibromatous) proliferation of spindle cells reacting to the tumor infiltration. Clinically, patients may present with abdominal/pelvic mass, ascites, or symptoms related to the primary malignancy; sometimes the ovarian metastasis is discovered before the primary tumor is identified. Elevated tumor markers such as CEA and CA 19-9 may be seen, and CA-125 can be elevated as with many ovarian masses, creating diagnostic overlap with primary ovarian cancer. Immunohistochemistry helps distinguish primary ovarian mucinous tumors from gastrointestinal metastases: gastric/colonic tumors typically show CK20+/CDX2+/CK7- patterns, while primary ovarian tumors are usually CK7+/CK20-. Krukenberg tumors indicate stage IV disease from the primary cancer and carry a poor prognosis, with median survival often less than a year. Management focuses on treating the primary malignancy; surgical resection of ovarian metastases may be considered for symptom palliation but does not typically confer significant survival benefit. This entity is high-yield for boards due to its classic association with signet ring cells and bilateral ovarian involvement, testing students' ability to recognize metastatic versus primary ovarian pathology.