Hidradenocarcinoma of the Chest With Axillary Lymph Node Metastasis: Report of 2 Cases and Systematic Literature Review of a Breast Cancer Mimicker.

Hidradenocarcinoma (HAC) is a rare malignant neoplasm originating from eccrine sweat glands, often presenting diagnostic challenges because of its resemblance to other malignancies, particularly breast cancer when occurring in the chest region. This report describes 2 cases of HAC with axillary lymph node metastasis, both initially misinterpreted clinically. The first case involved a 63-year-old woman with a sternal mass, near the right breast, initially suspected to be a sebaceous cyst. Histologic examination revealed a solid-cystic epithelial tumor with features suggestive of HAC, confirmed by immunohistochemical analysis. The second case concerned an 81-year-old woman with a subcutaneous growth in the sternal area, also diagnosed as HAC after histopathologic and immunohistochemical assessment. Both cases demonstrated strong estrogen receptor positivity, leading to the recommendation of hormonal therapy. A systematic review of the literature identified 21 similar cases of HAC in the chest wall, highlighting the diagnostic complexities and the potential for these tumors to mimic breast carcinoma. This review underscores the need for careful histologic and immunohistochemical evaluation to differentiate HAC from other malignancies, particularly in the breast region. Given the rare and the potential aggressive nature of HAC, early and accurate diagnosis is crucial for guiding appropriate therapeutic strategies and improving patient outcomes.