[Radiological features of breast cancer]

When considering typical features of malignant lesions, the radiologist must differentiate between invasive cancers consisting of mass lesions and ductal carcinoma in situ, typically appearing as microcalcifications. Common malignant features of invasive cancers include irregular shape and indistinct or spiculated margins. In microcalcifications, segmental distribution and pleomorphic shape are the features with the highest predictive value of malignancy. However, there is a broad spectrum of findings that confound the reliable differentiation between benign and malignant lesions. The American College of Radiology has established the Breast Imaging Reporting and Data System (BI-RADS) for standardizing radiological terms and reports in mammography screening. The Breast Imaging Reporting and Data System provides diagnostic categories that have implications for guidance regarding follow-up or biopsy of mammographic breast lesions. BI-RADS 3 lesions are considered probably benign with a malignancy risk < 2%. These findings can be followed up at predetermined intervals according to current recommendations. Suspicious lesions with a substantial probability, but without the classic appearance of malignancy, are classified as BI-RADS 4. Minimal invasive biopsy should be considered in patients with these lesions. BI-RADS 5 lesions are highly suggestive of malignancy. It is recommended that appropriate action should be taken for these most suspicious lesions. The accuracy of the mammography as the primary diagnostic tool can be increased by the use of ultrasound and physical examination. In some situations, MRI is helpful for further evaluation. However, classifying the lesions with precision is not trivial since overlap exists between malignant and benign features.