Violaceous Plaques and Breast Tenderness in a 71-Year-Old Breast Cancer Survivor

A 71-year-old woman presented for evaluation of breast tenderness and erythema. Her medical history was significant for a 4-cm, poorly differentiated, ER/PR/Her2-negative adenocarcinoma of the right breast treated with lumpectomy and adjuvant chemotherapy and radiation therapy a decade prior to presentation. Two years prior to her current presentation, the patient developed lymphedema of her right breast, which was treated intermittently with physical therapy. Over the past month, the patient had developed redness, warmth, tenderness, and swelling of the same breast. The patient denied fevers, chills, and nipple discharge. She was treated with oral clindamycin, 300 mg every 8 hours, for presumed cellulitis, without resolution, at which time she was referred to the dermatology department. A physical examination revealed several violaceous-indurated plaques on the right breast, with a dominant lesion surrounding the nipple (Figure 1 and Figure 2). A shave biopsy was performed and the sample sent for pathologic evaluation (Figure 3). What is your diagnosis?