Bennett JA, et al. - Researchers reviewed 17 cases of metastatic breast carcinoma to the ovary with signet ring cells, including 14 Krukenberg tumors (metastatic adenocarcinoma to the ovary containing ≥ 10% signet ring cells), to identify features indicative of mammary origin vs other possible primary sites. Krukenberg tumor usually arises from the stomach but can also originate from other sites. Patients ages ranged from 41 to 76 years. Among these patients, 14 had a history of invasive breast carcinoma. The investigators found that the cases lacked the features characteristic of gastrointestinal origin, such as extracellular mucin, intestinal-type glands, dirty necrosis, microcysts and goblet cell carcinoid-like foci, and had an overall morphologic picture strongly suggestive of mammary origin. The clinical history and immunohistochemical evaluation further supported the diagnosis.