Lobular breast carcinoma metastatic to the endometrium in a patient under tamoxifen therapy: A case report

Metastatic carcinomas to the uterus are rare and usually originate from nearby gynecologic sites, most commonly from the ovaries. Among non-gynecologic origins, breast tumors are the most frequent primaries, predominantly the lobular carcinoma type. A 69-year-old postmenopausal woman diagnosed with lobular breast carcinoma 5 years ago, status post modified radical mastectomy, and currently on tamoxifen therapy presented with post-menopausal bleeding. Subsequent endometrial biopsy confirmed the diagnosis of metastatic lobular breast carcinoma to the endometrium. Breast carcinomas rarely metastasize to the uterus, especially lobular carcinoma type. Abnormal uterine bleeding in a patient with known history of breast carcinoma and under tamoxifen therapy should prompt a complete diagnostic workup to rule out metastatic disease.