A breast biopsy may be recommended when the radiologist identifies a “lesion” or abnormality on the mammogram and/or breast ultrasound. While it is natural for a woman to feel anxious about the need for a breast biopsy, consider the fact that 70-80% of the lesions recommended for biopsy turn out to be benign. Unfortunately there is an overlap between what some benign and some cancerous lesions look like on the mammogram, and that is why so many benign biopsies are performed.
Breast cancer may have several faces on imaging: it may appear as calcium, or as a mass with or without calcium, as a distorted tissue pattern, or asymmetric tissue density. The significance of calcium on the mammogram is as a sign of activity at the cellular level. This is usually benign activity. However, a percentage of early breast cancers called DCIS (Ductal Carcinoma In Situ) may present as calcium only. This is cancer in its earliest curable stage. When the pieces of calcium are tightly grouped, new or changing and varied in appearance, there exists a higher likelihood that they represent this early type of cancer, and biopsy will be recommended. A mass or tumor is any space-occupying lesion. If fluid-filled, it is a benign cyst. If composed of solid tissue or cells, it may be benign or malignant. If a solid mass is new, enlarging or irregular in contour and content, a biopsy will be recommended. Most invasive breast cancers will present with a mass on imaging. Distortions and asymmetries are more subtle imaging findings of breast cancer, where breast imaging experience and expertise is crucial to avoid delays in diagnosis.