Invasive ductal carcinoma (IDC) is the most common breast cancer in men, though it accounts for
less than 1% of breast carcinomas diagnosed annually in the U.S. Only one prior case has reported IDC developing
in the same breast following surgical removal of a benign neoplasm. This report documents a rare case of IDC occurring
at the site of a previously excised benign tumor in a 93-year-old man. Case description - A 93-year-old male
presented with newly diagnosed left breast cancer, confirmed as IDC by mammogram, ultrasound, and biopsy. His
history included gynecomastia at age 20 and excision of a left-sided breast lump, reportedly a teratoma, in his late
50s. He underwent a left mastectomy with sentinel node biopsy. Pathology revealed IDC, grade 2, 2.5 cm, margins
>10 mm, node-negative (0/6), ER 90% (strong), PR 85% (strong), HER2-negative, Ki-67 15%, Magee score 14,
stage IIA (pT2N0). He recovered without complications and had well-controlled pain. Discussion - IDC developing
at a prior benign tumor site is rare but highlights the need for long-term surveillance in patients with breast
lesions. Studies suggest benign breast disease (BBD) increases cancer risk, with 9.4% of BBD cases progressing
to malignancy in women. While no male data exist, the recurrence rate of benign tumors in women is 3–6%, with
an estimated recurrence with transformation risk of 0.28–0.56%. The rarity of this case and long interval between
tumors emphasize the need for vigilance in men with prior benign breast tumors.
