In parts 1 and 2 of this three-part series of articles, we sought to establish, on the basis of embryologic, anatomic, and histologic considerations, that the breast qualified as a distinctive region of skin and subcutaneous tissue and not as an organ unto itself. In this third part, we endeavor to compel to the conclusion that pathological processes in the breast are the same, fundamentally, as those in the rest of the skin and subcutaneous fat.