Synchronous breast cancer and breast lymphoma are rare. It is of high rate of misdiagnosis in clinical practice. Here we present two cases with this presentation. They are both middle-aged women, with stage I invasive ductal carcinoma of the breast. One patient happened to have primary breast lymphoma (PBL); the other was secondary breast lymphoma (SBL). Their pathology and immunohistochemistry (IHC) findings supported the diagnosis of multiple primary carcinoma. Both patients had a surgery. Then they both received CHOP regime chemotherapy and subsequent endocrine therapy.