Abstract
Routine mammography screening in a 63-year-old woman showed a small breast mass with indistinct borders. Ultrasound showed a triangle mass, 12 mm in size, which had somewhat unclear anterior borders with focal strong high echoes at their center, multiple punctate echogenic foci in the internal low echoes, and slightly attenuated posterior echoes. Magnetic resonance images (MRI) of the tumor showed a hypointense pattern both on T1- and fat-suppressed T2-weighted images. Time-signal intensity images of MRI showed weak early enhancement followed by a persistent pattern. These imaging findings suggested that cancer cells with some kind of papillary structures would be present sparsely and diffusely in the fibrous background. After the pathological confirmation of malignant cells, the patient underwent a partial mastectomy and sentinel node biopsy. Postoperative pathological study showed that atypical cells growing in a tubular fashion spread sparsely and diffusely in the fibrous background extending to the tumor edges. In conclusion, by understanding how collagen fibers, fat, and cancer cells affect image depiction in each imaging modality, diagnostic physicians can accurately predict the pathological findings even of small breast cancer.