Detection of a breast mass accompanied by a contralateral axillary lymphadenopathy presents a dilemma because of the possible presence of an occult breast cancer on the same side as the axillary lymphadenopathy. A patient presented with an axillary lymphadenopathy from an occult breast cancer and a synchronous contralateral breast cancer, for which the differential diagnosis was established through a significant difference in estrogen and progesterone receptor levels. The patient was treated with neoadjuvant chemotherapy followed by bilateral modified radical mastectomy, adjuvant chemotherapy, and adjuvant radiation therapy. She is alive and free of disease 1.5 years after the diagnosis.