Cytomorphology of benign breast disease.

Fine needle aspiration biopsy is a widely used technique for the initial diagnosis of mammary lesions. The majority of patients undergoing fine needle aspiration biopsy of a breast lesion will have a benign disease of the breast. This article provides a review of the cytomorphologic features in a variety of benign breast lesions,and discusses the commonly encountered differential diagnoses on aspiration biopsy. Topics discussed include inflammatory and reactive conditions, treatment-induced changes, pregnancy-related changes, benign proliferative lesions, and benign neoplasms of the breast.