Report of a nipple nevus and an overview of accessory mammary tissue.

Supernumerary nipples, also known as accessory nipples, are the most frequently encountered congenital anomaly of the breast. Once associated with fertility or divine powers, they are now widely held to be of cosmetic significance only. During the past 20 years, however, there has been a steady number of articles reporting the suspected association of supernumerary nipples with numerous benign and malignant medical conditions. We describe a previously unreported accessory nipple variant occurring as a nevoid nodule surmounting an otherwise normal primary nipple. The patient was otherwise healthy. The embryogenesis of this anomaly is hypothesized to result from in utero nipple dichotomy, rather than a failure of regression along the embryonic milk line.