Nipple Discharge—When to Worry and When Not to: a Pictorial Review

Nipple discharge is the third most common complaint in patients with symptoms pertaining to breast diseases, accounting for 7% of overall breast symptoms. Nipple discharge may be spontaneous or induced, unilateral or bilateral, and of varied colors depending on the etiology. Also, it may be physiological or pathological. Both benign and malignant processes can lead to nipple discharge, with benign pathology accounting for more than half of the cases. The gold standard of management is surgical duct excision. In conjunction with good clinical history and laboratory work-up, imaging, i.e., mammography and sonography, can conclusively differentiate between benign and malignant etiology, and thus guide further course of management. MRI has been gaining a wider role in its evaluation; however, it is limited by cost and lack of availability. The purpose of this article is to comprehensively elucidate the various causes of nipple discharge and their imaging features on mammography and sonography, as a guide to further management.