Breast lesions that may be cancerous generally possess a higher elastic modulus than the surrounding tissue. Thus, they are sensed to move differently from the surrounding tissue during finger-based palpation. Since the palpation is subjective in nature, a method using ultrasound for detection of the differential motion associated with hard lesions is proposed. It is intended that regions of detected 'lump' be highlighted on top of a conventional B-mode image so that the user can positively associate palpated lumps with specific regions on the anatomical B-mode image. We detect the differential motion associated with a lesion by detecting a local abnormality in a map of image-to-image correlations as the transducer is swept in an elevational direction. Experiments were performed with three different tissue mimicking phantoms. The results indicate that the location of the mobile lesion can be successfully estimated whereas immobile lesions are not very detectable. This approach is simple and requires only a short period of time for each scan. It has practically no theoretical incremental cost.