A girl aged 11 years presented with a painful erythematous mass in the left outer fold of the vulva that had been increasing in size over the past 6 months. It was diagnosed as Bartholin’s cyst, and each episode was managed with antibiotherapy and analgesia. Subsequently, a detailed history-taking revealed cyclical changes synchronised with the menstrual cycle. The physical examination evinced the presence of a fully formed areola and nipple (Fig. 1A). The ultrasound examination found ectopic breast tissue. The patient underwent complete surgical resection (Fig. 1B and C). The histological examination confirmed the presence of mammary glands lined with cuboidal epithelium.
The incidence of ectopic breast tissue is 1%–6% and it is twice as frequent in female compared to male individuals. It results from the incomplete involution of the milk line outside the chest, and can develop anywhere along this line.1 It is predominantly found in the axillary region (60%–70%), and other locations are extremely rare, especially in the paediatric population.1,2 It is associated with a wide range of symptoms, depending on its location and components. The lesions become symptomatic during menarche and may undergo periodical changes synchronised with the menstrual cycle.2 Its development is hormone-dependent, so it may undergo pathological changes, benign (fibroadenoma, fibrocystic changes, phyllodes tumour or intraductal papilloma) or as well as malignant (carcinoma, adenocarcinoma or sarcomatous degeneration). At present, there is no evidence that these changes are more frequent in supernumerary breasts.3 A pathological and histological examination is essential. An ultrasound examination may be useful to rule out associated malformations or masses in the genitourinary system.2
