Imaging findings and management of primary breast cancer in accessory axillary breast tissue

Primary breast cancer presenting in ectopic axillary breast tissue comprises < 1% of all breast cancers each year. These rare presentations are easily mistaken for axillary nodal metastasis, which might be detrimental to the patient. We present a series of 3 patients all treated at a single tertiary cancer center and propose a management algorithm for this unusual presentation. Comprehensive imaging, including magnetic resonance imaging, to rule out occult in-breast disease, is key to the correct diagnosis. Mastectomy is not required in this special population, however, because of the large volume of accessory tissue removed intraoperative drain placement is recommended. Sentinel lymph node biopsy can be successfully performed using a standard dual technique of radioactive tracer and dye. Whole breast radiation is not requisite and systemic therapy should be based on pathologic tumor, node, metastases staging.