Metastasis of breast cancer to renal cancer: report of a rare case

Abstract

Tumor-to-tumor metastasis (TTM) is a rare phenomenon. We present a case of an invasive ductal carcinoma (IDC) of the breast metastasizing to a clear cell renal cell carcinoma (RCC). Breast cancer (BC) metastasis to the RCC is rarely reported, especially in resected kidney tumor. In several cases reported, IDC was the exclusively histologic type of BC metastasized to RCC. It seems that the different molecular type of IDC doesn't affect the metastatic tendencies to RCC. TTM was an indicator of diffuse disease. For any patient with a history of breast cancer, especially with multi-organs metastasis, resection of kidney tumor should be carefully considered.

Keywords: Breast cancer; renal cell carcinoma; tumor-to-tumor metastasis.

Figure 1

A. Chest CT: mediastinal lymph node enlargement, consider for breast cancer metastasis. B. Abdomen CT: intrahepatic nodules, consider for metastatic carcinoma. C. CT scan with the left renal mass, 3.0 cm in diameter. D. Abdomen CT after RCC operation. E. Metastatic disease progressed in the liver (4 months after RCC operation). F. Mediastinalmetastatic disease progressed (4 months after RCC operation).

Figure 2

A. One small distinct lesion circumscribed by the RCC. HE (× 100). B. Immunohistochemical (IHC) staining of RCC: positive forVimentin (× 100). C. IHC staining of RCC: positive for CD10 (× 100). D. IHC staining of the metastatic focus: positive for ER (× 100). E. IHC staining of the metastatic focus: positive for mammaglobin (MGB) (× 40). F. IHC staining of the metastatic focus: positive for CK7 (× 100).