As a consequence of the incomplete resolution of embryologic mammary ridges, ectopic breast tissue can be present anywhere along the "milk line", including the axillary region. Aberrant breast tissue can develop with any disease that affects the normal breast, including a breast carcinoma. A carcinoma of aberrant breast tissue is rare, but should still be investigated and treated properly with respect to other breast cancers in the embryonic milk-line. Herein is reported our recent experience of a carcinoma originating from aberrant breast tissue in the right axilla. An abnormal nodule around the periphery of the normal breast should be suspected as a breast carcinoma and differential diagnosis and properly treated.