Metastasis of lobular breast carcinoma to the uterus in a patient under anastrozole therapy.

BACKGROUND: Metastasis of extragenital neoplasms to the uterus are rarely encountered, and usually occur as a manifestation of advanced disease. Lobular carcinoma is the most common type of breast cancer that metastasizes to the uterus. CASE REPORT: We report on a 56-year-old woman who 3 years previously was diagnosed with invasive lobular carcinoma of the breast and was treated with surgery followed by chemotherapy and radiotherapy. While the patient was on adjuvant anastrozole therapy for 2 years, she complained of vaginal bleeding. Because of endometrial thickening and a uterine leiomyoma detected during abdominal ultrasonographic ex-amination, a total hysterectomy with bilateral salpingo-oophorectomy was performed. Histopathologic examination of the specimens revealed carcinoma infiltration of the myometrium, endometrium, cervix, uterine tube, and left ovary. Immunohistochemical staining of tumoral cells with pancytokeratin and gross cystic disease fluid protein (GCDFP-15) proved the diagnosis of metastatic lobular breast carcinoma to the uterus. CONCLUSION: To our knowledge, this is the second case of lobular breast carcinoma metastasized to the uterus under anastrozole therapy. In women with lobular breast cancer under adjuvant anastrozole therapy, who present with vaginal bleeding, uterine metastasis of lobular carcinoma should be considered in the differential diagnosis.