The cells or tissue removed through needle or surgical biopsy are promptly sent (along with the x-ray of the specimen, if one was made) to the pathology laboratory. If the excised lump is large enough, the pathologist can take a preliminary look by quick-freezing a small portion of the tissue sample, making it hard enough to slice into razor-thin sections that can be examined under the microscope. A "frozen section" provides an immediate if provisional diagnosis, and the surgeon may be able to give you the result before you go home.
A frozen section is not 100 percent guaranteed, however. A more thorough assessment will take a few days longer, while the pathologist processes "permanent sections" of tissue that can be examined in greater detail.
When the biopsy specimen is small-as is often the case when the abnormality consists of mammographic calcifications only-many doctors prefer to forego a frozen section so the tiny specimen can be analyzed in its entirety.
The pathologist looks for abnormal cell shapes and unusual growth patterns. In many cases the diagnosis will be clear-cut. However, the distinctions between benign and cancerous can be subtle, and even experts don't always agree. When in doubt, pathologists readily consult their colleagues. If there is any question about the results of your biopsy, you will want to make sure your slides have been reviewed by more than one pathologist.