A breast mass or lump may be reported by a patient or detected by a physician on routine clinical examination. Breast lesions may also be detected by a screening mammography. Whether a mass is actually present can be very difficult to determine. In the absence of a surgical scar, a mass associated with skin dimpling is malignant until proven otherwise. A mass that changes with the menstrual cycle or has been present and stable for years is more likely to be benign. A change in the overall size of the breast is usually not a sign of cancer. Whether a mass is solid or cystic cannot be determined by clinical examination alone. Only an ultrasound (not a mammogram) can determine whether a mass is cystic or solid, which is why palpable masses must be evaluated by both mammogram and ultrasound. Retrospective and prospective studies have shown a relative risk of breast cancer of 1.5 to 1.6 for women with benign breast disease as compared with women in the general population. Women diagnosed with LCIS should undergo yearly mammography. Digital mammography with additional screening ultrasound should be considered in women who have dense breasts. Currently, there is no evidence that MRI should be used for intensified surveillance as has been recommended in women with a genetically increased risk. Ductal lavage (DL) is a new method for the sampling of breast epithelium. Data regarding its sensitivity in the detection of epithelial abnormalities, including carcinoma in situ, remain limited. The use of DL remains investigational and close follow-up should be continued for all patients undergoing DL even if the results are benign. Excision of PASH after CNB may be considered for patients with symptoms, enlarging lesions, or lesions classified as Breast Imaging Reporting and Data System (BI-RADS) 4 or 5. PASH diagnosed by CNB allows selected patients to avoid excision.