A 56-year-old woman noticed soreness and swelling in the right nipple. Two weeks later, she noticed a mass in the outer lower region of the right areolar area, which was excised and the pathology of which was consistent with diffuse large B cell lymphoma (DLBCL). She was admitted when the right nipple mass was noted to be increasing, and was diagnosed as having stage I lymphoma. Her nipple mass was excised, and the pathology was consistent with DLBCL. CHOP therapy was administered three times and she was judged as having complete remission. Malignant lymphoma accounts for 0.15-0.17% of primary breast malignancies. Though the nipple and areolar area seem to be a rare primary site, this should be recognized as a sentinel zone for malignant lymphoma.