Pure Apocrine Carcinomas Represent a Clinicopathologically Distinct Androgen Receptor-Positive Subset of Triple-Negative Breast Cancers.
Apocrine carcinomas comprise ∼1% of all breast cancers and are characterized by large cells bearing abundant eosinophilic granular cytoplasm, round nuclei, and prominent nucleoli. They are typically estrogen receptor/progesterone receptor/HER2 negative, making them unresponsive to typical hormonal or HER2-based chemotherapy. However, this subtype of triple-negative breast cancers expresses androgen receptor (AR), a feature not shared by most nonapocrine triple-negative cancers (NA-TNCs). AR therefore represents a potential diagnostic tool and therapeutic target for apocrine breast carcinoma. All pure apocrine carcinomas diagnosed during a 10-year period were reviewed, and clinicopathologic characteristics were compared with a control group of 26 NA-TNC cases. Twenty apocrine carcinomas were identified (∼0.8% of all breast cancers). The mean age at diagnosis was 69.3 years for apocrine carcinomas and 56.7 years for NA-TNC. All apocrine carcinomas and no NA-TNC were AR positive. The proportions of apocrine carcinoma grades varied, with G1 being seen in 15% of patients, G2 in 55%, and G3 in 30%. In contrast, 100% of NA-TNC cases were G3. The majority of apocrine carcinomas presented at low T stage (T1: 70%; T2: 20%; T3: 10%; T4: 0%), whereas NA-TNC cases more often presented at T2 or higher (T1: 46.2%; T2: 30.8%; T3: 11.5%; T4: 11.5%). Thirty percent of apocrine carcinomas and 30.8% of NA-TNCs had nodal metastases at presentation. Apocrine carcinomas had a favorable clinical prognosis, with 80% of patients showing no evidence of disease-related morbidity or mortality (mean follow-up: 45.2 mo). Pure apocrine carcinomas represent a clinicopathologically distinct subgroup of triple-negative breast cancer characterized by AR positivity. When compared with NA-TNC, apocrine carcinomas more often present in older women with lower grade and T stage, a group in which a more conservative treatment regimen is often desired.
Departments of *Pathology †Hematology/Oncology, University of Virginia, Charlottesville, VA.
Anne M
AM
Mills
Chelsea
C
E Gottlieb
Scott
S
M Wendroth
Christiana
C
M Brenin
Kristen A
KA
Atkins
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001050:Apocrine Glands / Q000473:pathology; D014408:Biomarkers, Tumor / Q000032:analysis; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D011944:Receptors, Androgen / Q000096:biosynthesis*; D046888:Tissue Array Analysis; D064726:Triple Negative Breast Neoplasms / Q000473:pathology*
C410798:AR protein, human; D014408:Biomarkers, Tumor; D011944:Receptors, Androgen