Breast Cancer of an Accessory Nipple

A 42-year-old woman presented to the breast clinic with a mass posterior to an accessory nipple (arrow) that had been progressively enlarging over the past year. On physical examination, the patient had an irregular, hard mass, 3 cm by 4 cm, overlying the chest wall. The mass was inferior to the right inframammary fold and directly posterior to the accessory nipple. There were focal erythematous skin changes, suggesting local skin involvement. The patient also had a palpable right axillary lymph node. A punch biopsy of the mass was performed, which revealed a poorly differentiated adenocarcinoma, consistent with invasive ductal carcinoma . . .