RESUMEN
Primary accessory breast cancer is an extremely rare pathology, representing less than 1 % of all breast cancers, and it is found in more than 90 % of cases in the axilla. The diagnosis of accessory axillary breast cancer (AABC) is often late and at an advanced stage with an average delay of 40.5 months. Histological sampling and immunohistochemical results confirm the diagnosis. Most patients are diagnosed with stage II disease or higher, so it is considered to have a poor prognosis. There is no specific management for AABC; it follows the guidelines for orthotopic pectoral breast cancer. We therefore report the case of a 50-year-old woman diagnosed with grade II invasive ductal carcinoma found in accessory axillary breast, treated by wide local resection and sentinel lymph node dissection.