Breast metastases of extramammary malignant neoplasms are rare, with an incidence of 0.3%–2.7% among all malignant mammary tumors. Breast metastases from gastric carcinoma are very rare (<0.1%), and this event is even rarer during pregnancy. Herein, we describe a 39-year-old Caucasian woman with a history of an Epstein-Barr virus-associated gastric carcinoma (EBVaGC) that was characterized by prominent tumor infiltrating lymphocytes. Three years after undergoing radical surgery, the patient developed bilateral breast nodules during her pregnancy. A breast biopsy was performed, and histology confirmed a diagnosis of EBVaGC; tumor cells showed positivity for cytokeratin 8/18 and E-cadherin, and negativity for cytokeratin 7, cytokeratin 20, cytokeratin 5/6, caudal type homebox 2, androgen receptor, mammaglobin, gross cystic disease fluid protein-15, and estrogen and progesterone receptors. We also discuss the main diagnostic pitfalls. To our knowledge, this is the first report of an EBVaGC with lymphoid stroma that developed breast metastases during pregnancy.

中文翻译：

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妊娠期间 Epstein-Barr 病毒相关胃癌的双侧乳房转移：有没有办法解决它的疯狂？

乳腺外恶性肿瘤的乳腺转移很少见，在所有乳腺恶性肿瘤中的发生率为0.3%～2.7%。胃癌的乳腺转移非常罕见（<0.1%），这种情况在怀孕期间更为罕见。在此，我们描述了一名 39 岁的白人女性，她有 Epstein-Barr 病毒相关胃癌 (EBVaGC) 的病史，其特征是肿瘤浸润淋巴细胞明显。在接受根治性手术三年后，患者在怀孕期间出现了双侧乳房结节。进行了乳房活检，组织学证实了 EBVaGC 的诊断；肿瘤细胞对细胞角蛋白 8/18 和 E-钙粘蛋白呈阳性，对细胞角蛋白 7、细胞角蛋白 20、细胞角蛋白 5/6、尾型 homebox 2、雄激素受体、乳房珠蛋白、囊性病变液蛋白 15 和雌激素和孕激素受体。我们还讨论了主要的诊断陷阱。据我们所知，这是 EBVaGC 与淋巴基质在怀孕期间发生乳腺转移的第一份报告。