Large Congenital Melanocytic Nevus on the Breast Sparing the Nipple and Areola.

Abstract

Divided nevus is a rare entity that has been described for a special appearance of congenital melanocytic nevi (CMNs) occurring on the eyelid and penis. It is presumed that the formation of divided nevi is related with the embryologic development of the eyelid and penis, thus giving a hint about the occurrence time of CMN in utero. This article focuses on a formerly undescribed observation of another special clinical appearance of CMN discussing possible relation with embryogenesis. The data including photographic documentations of a total number of 86 patients with large CMN seen in a single center were reviewed according to the involvement of the nipple and areola by the main mass of the nevus and associated satellite lesions. Eight patients presented with CMNs involving one (n=6) or both (n=2) breast region. In all of them, CMN surrounded the nipple-areola complex without involving these structures. Furthermore, satellite nevi have not been observed on the nipple and areola in any of the 86 patients. We presume that different developmental time periods of the breast and the nipple-areola complex and the occurrence of the melanocytic lesion before the embryologic development of nipple-areola complex could explain our observation of CMN sparing the nipple-areola complex. The term "nipple-sparing nevus of the breast" is suggested for this special clinical appearance of CMN.