Figure 2b. Mammograms and a sonogram in a 57-year-old woman with a lump at the 5-o’clock position in the left breast. (a) Craniocaudal and (b) mediolateral oblique mammograms of both breasts. The glandular tissue was considered to be of high density. A subtle mass may have been present on the initial mammogram, best seen on the mediolateral oblique projection. (c) Initial mediolateral oblique mammogram (left) and mediolateral oblique mammogram obtained 4 months later (right). An ill-defined mass (arrow) is seen in the inferior left breast. (d) Transverse sonogram in the lateral lower quadrant demonstrates an ill-defined hypoechoic 4.5-cm mass. The arrows delineate two lobulations within the mass. The crosshairs depict the anteroposterior dimension (2.9 cm) of the mass. The histopathologic diagnosis was stage T3 invasive lobular carcinoma.