Supernumerary Breast Cancer

A 61-year-old patient presented with a left inframammary tumor measuring 2 cm, with a supernumerary nipple and cutaneous retraction. Mammography identified no breast lesions. Magnetic resonance imaging detected a left inframammary nodule measuring 14 mm with pathologic uptake curves (Fig. 1). A core needle biopsy provided the diagnosis of invasive ductal carcinoma (IDC). The surgical treatment involved excision of the supernumerary gland (IDC, free margins, negative hormonal receptors, positive HER2) and selective biopsy of the sentinel lymph node (2 benign nodes) (Fig. 2; arrow: supernumerary nipple; star: tumor).

Fig. 1

Fig. 2

There have been few similar reports reported in the literature, with a malignization rate of 5%.