Inflammatory breast cancer in accessory abdominal breast tissue.

Accessory breast tissue results from failure of the embryologic mammary ridge, also known as the milk line, to involute. As a result, ectopic breast tissue can develop anywhere along this ridge, which extends from the axilla-the most common location-to the groin. Primary breast cancer in accessory breast tissue is uncommon but has been reported in multiple prior studies. We present a rare case of inflammatory breast cancer presenting in upper abdominal accessory breast tissue in women with a personal history of ipsilateral breast cancer, and highlight the challenges of both diagnosis and treatment of breast cancer in accessory breast tissue.