What happened, in summary

A 61-year-old man came to a breast clinic after 2 weeks of scaly, crusted, eczema-like changes on his left nipple and an underlying lump. His left nipple had been inverted for 2 years. He also had bilateral gynecomastia, a history of Klinefelter syndrome diagnosed during infertility evaluation, childhood thymus radiotherapy, prior right orchidectomy for an undescended testis, hypothyroidism, and osteoarthritis. His mother had breast cancer in her 40s. Examination found a 3 by 3.3 cm mass deep to the left nipple, without palpable axillary lymph nodes. Core biopsy confirmed invasive ductal carcinoma. Imaging of the right breast showed indeterminate calcifications, and sampling was nondiagnostic, so the surgical plan addressed both breasts. He underwent left modified radical mastectomy and simultaneous right simple mastectomy. Final pathology showed a completely excised 18 mm grade I invasive ductal carcinoma in the left breast, with direct extension into the nipple epidermis mimicking Paget disease. There was no vascular invasion, and 0 of 7 left axillary lymph nodes contained metastasis. The left tumor was estrogen receptor-positive and progesterone receptor-positive, with weak HER2 expression. The right breast contained intermediate-grade ductal carcinoma in situ, with the largest focus measuring 4 mm. He received adjuvant tamoxifen. Although mild left-arm lymphedema developed, he resumed normal life and had no locoregional recurrence after 5 years. Staging before surgery found no metastatic disease. The right-sided DCIS was discovered only after the prophylactic/simple mastectomy specimen was examined, making the operation both therapeutic for the left invasive cancer and diagnostic/definitive for the right breast abnormality.