Figure 4: Architectural distortion. A 62 year old woman, operated for stomach cancer two years earlier, also had metastatic colorectal cancer. She felt a thickening in the upper portion of her left breast. Figures 4.A-C: Left and right mediolateral and left craniocaudal mammograms. Corresponding to the palpable lesion, mammography shows an asymmetric density with architectural distortion in the upper-medial portion of the left breast measuring >40 mm. Figures 4.D,E: Microfocus magnification images of the typical architectural distortion with neither a central tumor mass nor associated microcalcifications. Figures 4.F,G: MRI shows a 12x15x16 mm region of contrast enhancement with persistent kinetics in the left breast, 5 cm deep to the nipple, in the upper-inner quadrant. Neither morphology nor contrast enhancement kinetics indicate malignancy, and the finding is smaller than the mammographic finding. Figures 4.H,I: Hand-held ultrasound shows a large malignant tumor, which on ultrasound guided 14-g core biopsy gave a histologic diagnosis of invasive lobular carcinoma. Figure 4.J: Specimen slice radiograph showing the architectural distortion. Figures 4.K,L: The corresponding large thin section histology images of the mastectomy specimen show a 62x42 mm moderately differentiated classic invasive lobular carcinoma associated with multifocal Grade 1 in situ cancer and LCIS. Biomarkers: ER/PR +ve, Her-2 -ve, Ki67 16 %. No LVI. The surgically removed sentinel node contained isolated cancer cells (pN 1). Surgical margin free from cancer: 25 mm.