A supernumerary nipple is the aborted beginning of an additional nipple along the mid-clavicular line of the thorax. The hyperpigmented macule may have features more or less descriptive of a fully formed nipple, and occur a couple centimeters below the usually placed nipple. They are most often singular, and unilateral.
Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.