A 47-year-old woman presented to our institution with a 1-month history of swelling and a painless skin plaque on her left breast. 6 years earlier, the patient had been treated for luminal A invasive ductal carcinoma in the superomedial quadrant of the left breast; she had neoadjuvant chemotherapy, breast-conserving surgery, radiation therapy—a whole breast dose of 50 Gy plus a 10 Gy boost to the tumour bed—and oral tamoxifen. The patient had been found to have no recurrence of the tumour at any subsequent follow-up appointments.