Apocrine Carcinoma of the Breast: A Case Report and Review of the Literature

Background: Apocrine carcinoma of the breast is a rare and distinct subtype of invasive ductal carcinoma characterized histologically by large tumor cells with abundant eosinophilic granular cytoplasm and prominent nucleoli. Accurate diagnosis and immunohistochemical profiling are essential for distinguishing this entity from other breast cancer subtypes. Emerging evidence suggests a potential therapeutic role for androgen receptor (AR)-targeted treatments in managing this disease. Case Presentation: The patient was a 55-year-old woman with no significant past medical history who presented for a routine physical examination. A screening mammogram revealed a 1.2 × 0.8 × 0.6 cm superficial mass in the upper outer quadrant of the right breast, along with scattered coarse microcalcifications. A core needle biopsy was performed, and histopathological analysis confirmed the diagnosis of apocrine carcinoma of the breast, a rare subtype of invasive ductal carcinoma. Immunohistochemistry (IHC) demonstrated strong androgen receptor (AR) positivity and negativity for estrogen receptor (ER), progesterone receptor (PR), and HER2. The patient subsequently underwent surgical excision of the tumor. Postoperative recovery was uneventful, and the patient is currently under close clinical follow-up with consideration for AR-targeted therapy in the context of receptor status. Conclusions: Through a review of the current literature, we highlight the key histopathological, molecular, and clinical features of apocrine breast carcinoma. This case study underscores the importance of accurate diagnosis and comprehensive immunohistochemical analysis in guiding effective treatment strategies. The consistent expression of AR in these tumors supports further exploration of AR-targeted therapies as a promising treatment avenue.