Diagnostic Pitfalls of Metastatic Lobular Breast Carcinoma to the Endometrium in a Patient on Long-Standing Tamoxifen Therapy

Abstract

Metastatic carcinoma from extragenital sites to the uterus, particularly the endometrium, is rare and usually a sign of advanced disease. It is necessary to differentiate between metastatic and primary tumours since the treatment and prognosis are entirely different. We discuss a case of a 61-year-old woman who presented with postmenopausal bleeding due to metastatic breast cancer to the endometrium. She had been diagnosed with breast cancer and on tamoxifen for six years. This case highlights the possibility of isolated breast cancer metastasis to the endometrium without ovarian involvement and the overlapping histological features due to tamoxifen therapy. Abnormal uterine bleeding in a case of breast cancer should raise the suspicion of metastatic breast disease. The immunohistochemical study is critical to support the microscopic findings in conjunction with clinical history and radiological findings.