Synchronous breast invasive ductal carcinoma and clear cell renal carcinoma: case report and a review of literature.

Multiple primary tumors' incidence is rare, yet more rare is the incidence of multiple primary malignant tumors. Co-occurring tumors can be divided into synchronous and non-synchronous. Synchronous tumors are those tumors that present within a period not >6 months from each other. To define synchronous malignant tumors: metastasis should not be present, both tumors have to show criteria of malignancy, and they should differ pathologically from each other. Breast cancer is the most common tumor to be associated with other primaries especially; colorectal cancer, endometrial and ovarian cancer, yet the occurrence of invasive ductal carcinoma with clear cell renal cancer is uncommon. In our case, we present a 59-year-old female with invasive ductal carcinoma and clear cell renal carcinoma.