Synchronous metastasis from lobular carcinoma and primary carcinoma of the endometrium in a patient after tamoxifen therapy.

Patients treated with tamoxifen often experience vaginal bleeding, generally because of benign endometrial lesions or, less often, because of endometrial carcinoma. A rare cause of vaginal bleeding in these patients is breast carcinoma metastasis in an endometrial polyp. We describe a 67-yr-old patient with metastasis of lobular breast carcinoma in an endometrial polyp and papillary serous endometrial carcinoma, both diagnosed simultaneously in a uterine curettage. The coexistence of the 2 cancers was confirmed by pathologic study of the hysterectomy specimen. To our knowledge, this is the first reported case of the synchronous presence of the 2 neoplastic diseases. Endometrial biopsies performed for endometrial disorders in patients who have breast cancer and have received tamoxifen should be studied carefully to avoid underdiagnosis.