Breast metastases: A rare manifestation of advanced uterine serous carcinoma

Metastasis of non-mammary tumors to the breast are uncommon, representing <1% of all breast tumors. Breast metastasis are associated with advanced disease and poor prognosis regardless of the origin of the primary tumor. Uterine cancer metastasis to the breast is an extremely rare finding and has not been reported in the case of serous histology. Here, we review two cases of uterine serous carcinoma metastatic to the breast. Both patients presented with breast-specific complaints including pain and palpable mass and were found to have widely metastatic disease. Tissue biopsy and immunohistochemistry consistent with primary uterine serous carcinoma confirmed the diagnosis of metastasis in both cases. Our findings suggest hematogenous metastasis to the breast is a late phenomenon in the course of endometrial carcinoma and associated with the development of disease at multiple sites. This emphasizes the importance of complete evaluation in patients presenting with breast complaints and known history of malignancy, as this may be the only presenting symptoms in patients with widely metastatic disease.