Background: Ectopic breast tissue is a rare condition in the Caucasian population. The most frequent form is polythelia (supernumerary nipples), whereas polymastia (complete supernumerary breasts) is more uncommon. They are usually benign asymptomatic lesions that go undetected until pregnancy or lactation. However, they are under the same hormonal influence as normal breast tissue and therefore are susceptible to malignant changes.
Case: a 12-year-old girl presented bilateral axillary polymastia and polythelia, detected with puberal changes. Surgical removal was postponed until the end of puberal development.
Summary and conclusions: Polymastia is a rare condition that can have psychological consequences, especially in adolescents. It has been associated with other malformations and malignant tumours, so surgical removal is usually recommended.
Keywords: Ectopic breast tissue; axillary tumour; polythelia; supernumerary breasts; polymastia.
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