Apocrine change is seen in a wide spectrum of breast lesions, ranging from microscopic cysts to invasive carcinoma. This article reviews the range of apocrine lesions and discusses the clinical significance of these lesions. Although apocrine change in many cases does not present any diagnostic difficulty, apocrine proliferations demonstrating cytologic atypia can be particularly challenging. The histologic criteria that have been proposed to foster reproducibility in categorizing such lesions are reviewed. This review attempts to clarify the terminology that has been applied to a range of benign lesions, including sclerosing adenosis and complex sclerosing lesions, containing foci of apocrine change. Malignant apocrine lesions, including both in situ and invasive carcinoma, are also discussed.
Apocrine change in the breast is seen in a broad spectrum of lesions, from microscopic cysts to invasive apocrine carcinoma. Most of the lesions are easy to interpret and present little diagnostic difficulty. A minority of proliferative apocrine lesions, however, can present particular diagnostic challenges, especially if cytologic atypia is evident. Not only are some of these lesions difficult to categorize, but there is controversy regarding their risk associations for subsequent carcinoma development.1
The purpose of this review is to highlight the areas of consensus as well as the controversial areas and to clarify some of the confusing terminology and diagnostic criteria that have been applied to proliferative apocrine lesions. The literature dealing with in situ and invasive malignant apocrine lesions are also discussed.
From the Department of Pathology and Laboratory Medicine, Mount Sinai Hospital and University of Toronto, Toronto, Ontario, Canada.
Reprints: F. P. O’Malley, MB, FRCPC, Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario M5G 1X5, Canada (e-mail: firstname.lastname@example.org).