Clinicopathological Characteristics of Apocrine Carcinoma of the Breast

Purpose: Apocrine carcinoma of the breast is rare and there is confusion about the criteria of its histopathologic diagnosis. The purpose of this study is to investigate the clinical and pathologic characteristics of the disease. Methods: 9 patients diagnosed with apocrine carcinoma or apocrine carcinoma in situ and 1,009 patients diagnosed with non-apocrine carcinoma of the breast from April 1999 to March 2008 were retrospectively analyzed. Results: The mean age of the patients with apocrine carcinoma was 52.3 year. 5 patients (55.6%) among 9 patients with apocrine carcinoma were postmenopausal. There were 2,1 and 6 patients with stage 0, Ⅰ and Ⅱ disease, respectively according the TNM stage. These demographic and clinical differences between the patients with apocrine carcinoma and non-apocrine carcinoma were not significant. Only four patients (44.4%) were preoperatively diagnosed with apocrine carcinoma or apocrine carcinoma in situ. By surgical biopsy, additional 5 patients were diagnosed as apocrine carcinoma. In the immunohistochemical study, Bcl-2 was positive in one (12.5%) of 8 patients. p53 was positive in 4 (44.4%) of 9 patients. Expressions of estrogen and progesterone receptor were positive only in two patients (22.2%) with weakly positive staining. Androgen receptor was positively expressed in all cases (100%) of apocrine carcinoma. Overexpression of c-erb-B2 was detected in four patients. Conclusion: Treatment modality and prognosis of apocrine carcinoma are similar as non-apocrine carcinoma. But its preoperative diagnosis is more difficult than that of non-apocrine carcinoma and it shows different expression of hormone receptor. Further study is needed for the development of new hormonal therapy using androgen.