Early Nodal Metastasis in an 81-Year-Old Woman With Subcentimeter Retroareolar Invasive Ductal Carcinoma: A Case That Defies Indolence Expectations.

Retroareolar invasive ductal carcinoma (IDC) represents an anatomically distinct subset of breast cancers that may evade early clinical detection. In elderly patients, small, estrogen receptor (ER)-positive tumors with low proliferative indices are often presumed to follow an indolent course. We report the case of an 81-year-old woman diagnosed with a 0.6-cm Grade II/III retroareolar IDC exhibiting strong ER expression, low Ki-67 (~6%), and human epidermal growth factor receptor 2 (HER2) negativity, yet with synchronous axillary lymph node metastasis confirmed at initial biopsy. This case underscores the limitations of relying on tumor size, age, and proliferation markers alone to estimate metastatic risk and highlights the importance of comprehensive axillary evaluation, even in clinically and biologically favorable presentations.