iarjmcrIARJMCRIARJMCR2709-3220https://doi.org/10.47310/iarjmcr.2020.v01i01.001Accessory Breast Cancer Patient: Follow-Up Case ReportImanMoustafaMEssamBadawyAccessory breast is a congenital atavism ‎condition. Accessory breast tissue may be arising anywhere along the mammary line because of the failure ‎of complete maturation during embryogenesis. The malignancy in accessory breast tissue is considered as ‎primary breast cancer. Axillary breast cancer is not well recognized site of primary breast cancer.‎‏ ‏ This case report for a 55 year-old premenopausal female who presented with axillary immobile mass in her left axilla that diagnosed after extensive investigations as stage II B, ER, PR positive and HER neu positive poorly differentiated ‎accessory breast adenocarcinoma.‎ The patient was staged as stage II B and we followed NCCN guidelines 2013 for breast cancer in management, so our patient was surgically treated, followed by postoperative adjuvant chemotherapy in the form of 4 cycles doxorubicin and cyclophosphamide followed by 4 cycles of paclitaxel and 17 cycles trastuzumab. Subsequently radiotherapy was given followed by hormone therapy. We followed up the patient for 6 years and she is doing well. Accessory breast cancer is a rare disease and misdiagnosis of these cases is very immense and lead to extensive unnecessary investigations. Physicians have to be aware about these cases. Management of accessory breast cancer is according to the same guidelines for management of breast cancer. Follow up data should extensively encourage determining the prognosis of accessory breast cancer in comparison to usual breast cancer.