- The breast is an unusual site for primary non-Hodgkin's lymphoma. Carcinoma in the same breast after treatment for lymphoma poses therapeutic challenges, but there is only 1 case report in Japanese, which describes this occurrence. A 59-year-old woman was diagnosed with infiltrating ductal carcinoma of the breast after receiving doxorubicinand vincristine-based chemotherapy for ipsilateral primary large cell breast lymphoma. The cancer was of high grade histology, with immunohistochemistry staining 3+ positive for HER2/neu. After lumpectomy and sentinel node biopsy, adjuvant paclitaxel without anthracyclines was given but had to be stopped early because of neurotoxicity. Radiotherapy to the breast was administered, and a 1-year course of trastuzumab was planned. Breast cancer can occur after breast lymphoma. For primary breast lymphoma, cumulative doses of cardiotoxic and neurotoxic drugs should be limited to 3-4 cycles of chemotherapy, using treatment protocols for stage I-II large cell lymphoma. Consolidation radiotherapy should be considered at a dose curative for microscopic breast cancer.