MG, US, and post-surgical pathology results from a 38-year-old patient with a lump in her left breast. (A) Craniocaudal and mediolateral oblique MG of the left breast displayed lesions in the left outer breast, with multiple clusters of microcalcifications, unclear lesion boundaries (white arrows), and unknown lesion sizes. (B) MG of the right breast of the same patient. (C) The size of lesion was 3 cm by US. (D) Post-surgical pathological examination revealed adenosis of the breast complicated by fibroadenoma, with focal calcifications (HE staining, ×100). This represents a typical example of the inability of MG to correctly determine the lesion boundaries and size compared with pathological examination.