Supernumerary Nipple Presenting as a Vulvar Mass in an Adolescent: Case Report and Literature Review

Background: Ectopic breast tissues can be found along the embryonic mammary ridges and can occur in the vulva. While ectopic breast tissue is not uncommon, functional breast with overlying nipple located within the vulva is exceedingly rare. Case: A 17-year-old with undiagnosed hypothyroidism presents with vulvar mass draining milky white fluid. A small lesion with appearance similar to a skin tag is noted and milky fluid expressed. Biopsy and excision of this mass confirmed the presence of a functional supernumerary nipple. Summary and Conclusions: This appears to be the first reported case of a supernumerary nipple with symptomatic lactation in a non-pregnant adolescent. Supernumerary nipple should be considered in the differential diagnosis of a vulvar mass. Ectopic breast tissue in the vulva can undergo malignant transformation, therefore excision of this tissue is generally recommended.