Invasive Apocrine Carcinoma in a Young Female With Triple Hormone Receptor Positivity: A Case Report

Apocrine carcinoma (AC) of the breast is a rare histological subtype, classically characterized by androgen receptor (AR) positivity with estrogen receptor (ER) and progesterone receptor (PR) negativity. We report the case of a 35-year-old premenopausal woman who presented with a five-month history of a left retroareolar breast lump associated with intermittent serous nipple discharge. Clinical examination and breast imaging revealed a suspicious lesion, and core needle biopsy suggested invasive ductal carcinoma. The patient underwent nipple-sparing breast conservation surgery with axillary clearance. Histopathological examination demonstrated invasive AC, modified Bloom-Richardson grade 1, without lymphovascular invasion or nodal metastasis. Immunohistochemistry revealed an unusual triple hormone receptor-positive profile (ER-positive, PR-positive, AR-positive), with human epidermal growth factor receptor 2 (HER2) negativity and a low Ki-67 proliferative index. Adjuvant treatment included combination chemotherapy, radiotherapy, and dual hormonal therapy with tamoxifen and an AR inhibitor. This case highlights the diagnostic and therapeutic challenges of hormone receptor-positive AC and underscores the importance of comprehensive immunohistochemical profiling for individualized management.