Molecular and diagnostic features of apocrine breast lesions

Apocrine morphology in breast is observed in a wide variety of lesions ranging from simple cysts and atypical hyperplasia to invasive metastatic stages of disease. The accurate diagnosis of breast apocrine carcinoma remains controversial, mainly due to the subjectivity of histopathological criteria and the lack of sensitive and specific biomarkers for reliable categorization of this subtype of breast carcinoma. Thus, many efforts are currently being made to identify novel molecular marker signature(s) that can define apocrine carcinoma with high levels of accuracy and reliability, and determine with certainty the true clinical significance of these lesions. The purpose of this article is to review the data on apocrine lesions, with an emphasis on borderline apocrine differentiation. In particular, we address relevant issues in the context of the current state of research on benign and malignant apocrine lesions of the breast, with a focus on parameters for diagnosis and potential-targeted therapeutic options.