Bilateral axillary supernumerary breasts: About one case

Sara Lahsaini, Mohamed Amine Ennouhi, Abdenacer Moussaoui

Plastic Surgery Department, The Military Hospital Moulay Ismail of Meknes, Faculty of Medicine and Pharmacy of Fes-Morocco.

Corresponding author: Sara Lahsaini, MD, E-mail:

How to cite this article: Lahsaini S, Ennouhi MA, Moussaoui A. Bilateral axillary supernumerary breasts: About one case. Our Dermatol Online. 2023;14(e):e44.
Submission: 03.04.2023; Acceptance: 07.04.2023
DOI: 10.7241/ourd.2023e.44

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© Our Dermatology Online 2023. No commercial re-use. See rights and permissions. Published by Our Dermatology Online.


Polymastia or supernumerary breasts is an anomaly of the embryonic development of the mammary gland resulting in the absence of regression of the mammary buds on the milky line or outside of it. The axillary location is the most common. In the absence of nipple, engorgement and milky discharge, the diagnosis often remains difficult. Surgical treatment can prevent any complications such as cancer. We report a case of bilateral axillary supernumerary breasts while explaining the diagnostic difficulties of this pathology.

Mrs. M., 25 years old, mother of 2 children, with no particular history, who has bilateral axillary masses progressively increasing in size for 15 years, associated with a feeling of axillary swelling during the premenstrual period. The clinical examination finds a bilateral axillary swelling located on the middle axillary lines, of soft consistency, painless, adherent to the skin but mobile with respect to the deep plane, measuring 6 cm on the long axis on the right, against 5 cm on the left (Figs. 1a and 1b). An ultrasound performed revealed a bilateral fatty-looking axillary mass, probably suggesting a lipoma. A one-piece resection was performed. Histological examination showed the presence of fatty tissue with numerous lobules and glandular acini, without signs of malignancy (Fig. 1c). The evolution was favorable without recurrences with a follow-up of two years.

Figure 1: (a-b) Right and left axillary masses matching with a supernumerary breasts. (c) Histological image showing adipose tissue containing numerous lobules and glandular acini.

From the fourth to the sixth week of embryonic life, the mammary buds appear in pairs along the milky line or the mammary crest; It is a thickening of the ectoderm on each side of the ventral surface of the embryo [1] going from the future armpit to the future groin. However, other buds may appear whose persistence results in ectopic breast tissue. This tissue may contain the breast parenchyma, areola and nipple, or any combination of them.

In common with regular breast tissue, ectopic breast tissue undergoes physiological changes during gestation and the premenstrual period as well as pathological changes such as mastitis, fibroadenomas, fibrocystic changes, phyllodes tumors as well as malignant degeneration which represents 0.3 to 0.6% of all breast cancers [1,2]. When cancer occurs, it has a worse prognosis than on normal breast due to more frequent and faster lymph node metastases [1]. Polymastia can be at the thoracoabdominal level often at the armpits (5%) but more rarely on the face, back and thigh [3].

Although present from birth, polymastia is often diagnosed only after puberty, pregnancy or lactation due to hormonal action on the ectopic tissue [4]. Clinically it’s an engorgement, tenderness, pain in the affected area, milky discharge, but these signs are not always present, which poses a diagnostic problem, particularly with a lipoma, adenopathy, a subcutaneous cyst, a vascular malformation [5]. Ultrasound can guide the diagnosis but it cannot confirm the diagnosis [3,6], given the heterogeneous tissue character of the supernumerary breasts and this is the case of our patient whose clinico-radiological picture was not typical given the predominance of tissues adipose versus connective-glandular tissue on histological examination.

Supernumerary breasts can be associated with and even be the revealing phenomenon of other embryological abnormalities such as malformation of the urinary tract, abnormalities spinal and cardiovascular system, gastrointestinal, skeletal and skin diseases these are often sporadic cases, familial presentations have been reported in the literature [1].

The treatment of polymastia is controversial [3,4]; some authors recommend therapeutic abstention in the absence of complications, others recommend systematic surgical treatment in order to relieve the patient’s discomfort and prevent any complication, in particular malignant degeneration. Several surgical approaches are used, excision in one piece, liposuction, or both, but in all cases a histological examination of the part is mandatory with a long-term followed up.

The diagnosis of polymastia is difficult. Management is not well codified. Prophylactic surgical excision with histological study seems preferable to manage this anomaly.


The examination of the patient was conducted according to the principles of the Declaration of Helsinki.

Copyright by Sara Lahsaini, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


1. Garba A, Adamou H, Magagi A, Diongole H, Daou M. Axillary polymastia:a familial case. Ann Afr Med. 2017;10:1.

2. Nihon-Yanagi Y, Ueda T, Kameda N, Okazumi S. A case of ectopic breast cancer with a literature review. Surg Oncol. 2011;20:35 42.

3. Abita T, Lachachi F, Durand-Fontanier S, Maisonnette F, Valleix D, Descottes B. Àpropos d’un cas de seins surnuméraires axillaires bilatéraux. Morphologie. 2004;88:39 40.

4. Margi M, Azhary O, Oulahyane R, Cherkaoui A, Abdelhak M, Benhmamouch MN. Sein surnuméraire axillaire :àpropos d’un cas. Arch Péd. 2010;17:1162 4.

5. Janati Idrissi K, Quenum Souley L, Lahlou AM, Haloua M, Alami B, Lamrani AY, Maaroufi M, Boubbou M. Un cas rare de seins surnumeraires axillaires bilateraux :revue de la litterature. IOSR J Dent Med Scien. 2020;19:34-9.

6. Silverberg MA, Rahman MZ. Axillary breast tissue mistaken for suppurative hidradenitis:an avoidable error. J Emerg Med. 2003;25:51 5.


Source of Support: This article has no funding source.

Conflict of Interest: The authors have no conflict of interest to declare.

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