Ureteral metastasis from a HER2-enriched breast cancer: a rare case report.

Ureteral metastasis from breast cancer (BC) is very rare, and only a few cases have been reported. We report the first patient with ureteral involvement from human epidermal receptor 2 (HER2) enriched metastatic BC. A 51-year-old woman with HER2-enriched metastatic BC with liver metastasis was diagnosed at her first visit, achieving complete tumor regression by chemotherapy, anti-HER2 treatment, modified mastectomy and radiotherapy. After 1 year, she complained light left flank pain for 1 month, with an elevated cancer antigen 15-3 (CA15-3) level in blood. Computed tomography showed a left proximal ureteral lesion causing ureterectasis and hydronephrosis. A ureteroscope-guided biopsy of the ureteral lesion revealed poorly differentiated carcinoma from metastatic BC. Diagnosing ureter metastasis from BC were established by histopathology and immunohistochemistry. The flank pain and ureteral lesion were absolutely relieved after chemotherapy and anti-HER2 treatment, and CA15-3 level decreased to normal. Regular follow-up examinations every 3 months are performed at our outpatient clinic. With a 20 months follow-up, there has been no further progression up to now. Ureteral metastasis of BC shows nonspecific symptoms, and it is important to recognize this unusual manifestation so that timely appropriate treatment can be initiated in order to better prognosis. Chemotherapy plus anti-HER2 treatment are most effective for hepatic and ureteral metastasis from BC.