There are two main goals when it comes to making an accurate tissue diagnosis of either breast lumps or abnormal spots on the mammogram. The first goal is to distinguish between benign tissue and malignant tissue. The second goal is to make certain that if a lump proves to be a cancer, the biopsy should have been done properly in order to facilitate future treatment planning.
All too often, we see patients referred to us for whom an open surgical biopsy was done and a cancer was discovered on the final pathologic examination. This often results in a situation in which tumor extends to the edge of the specimen (margins are not clear), but since the original surgeon did not orientate the specimen (not anticipating a cancer), we don’t know exactly where to go to get clear margins. Under these circumstances, it is often difficult to determine if a patient is a candidate for breast conservation.
There are some cases in which the diagnosis is almost certainly benign and the patient is anxious to have the lump removed. An example could be a young woman with a clinically benign mass (such as a fibroadenoma). In such a case, it would be reasonable to remove the mass with an open excisional biopsy, and this avoids the cost and inconvenience of a two-step procedure. However, in the majority of lumps and suspicious spots on the mammogram, we do one of the following methods of tissue sampling, so that in the case of a malignancy, we can do appropriate pre-operative planning.
F.N.A. (or Fine Needle Aspiration)
A fine needle aspiration is simple office procedure that takes only a few minutes. A small gauge needle is placed in a breast lump/problem area, and cells from are extracted and placed on slide. The slide is sent directly to the pathologist, and a reading is often available in less than 2 hours. This simple and well-tolerated procedure can be quite effective in clarifying a clinical situation, and can thus expedite the treatment process.
The problem with this procedure is that it takes expert cytologists to interpret the results, and these experts are not available in many hospitals. Also, in about 30% of the cases, a definitive diagnosis cannot be made, and thus a core biopsy is required (see next section). We use the FNA in select cases in which we anticipate it will accelerate the diagnostic process.
Core Needle Biopsies
Rather than just extracting cells (as with the fine needle aspiration), the core biopsy takes a sample of tissue. This small sample of tissue is usually sufficient to provide a specific tissue diagnosis. In other words, this procedure not only distinguishes between benign and malignant findings (as does the fine needle aspiration), it also usually defines a specific pathologic condition. For example, in the case of a benign condition, it might diagnose a fibroadenoma, in which case nothing more needs to be done.
If the core biopsy states that the lesion of concern is malignant, it will typically differentiate between invasive or non-invasive cancer. It will also give information on the type of cancer present (i.e. ductal vs. lobular and high grade vs. low grade; see links to understanding your path report). In most cases, it will also allow for measurement of hormone receptors and other protein markers.
Core needle biopsies can be used to diagnose large tumors without any form of guidance (i.e. free-hand, in which the surgeon does inserts the needle by feeling where the tumor is). However in most cases, it is done with either ultrasound or x-ray guidance.
Ultrasound Guided Core Biopsy
If a lesion can be seen on ultrasound examination, we prefer to do an ultrasound guided core biopsy. This procedure is well-tolerated and is done with the patient lying comfortably on her back. A small titanium tissue marker is placed in the area of biopsy to show us where the biopsy was taken. The procedure usually takes only 10-15 mins and can be done under local anesthetic in the doctor’s office. Some post-biopsy bruising and tenderness can occur.
Stereotactic Core Biopsy
If a spot in question (usually calcifications) can only be seen on the mammogram, a stereotactic core biopsy is the procedure of choice. In this procedure, the patient lies on her stomach and her breast protrudes though an opening on the table. The biopsy device is below the table. A core needle is directed to within a millimeter of the area. An aperture in the needle opens up and the tissue in question is sucked into the needle and removed. A small titanium tissue marker is placed in the area of biopsy, just in case all of the tissue and/or calcifications are removed and the lesion later proves to be malignant. The location of the tissue marker guides the treatment team to the area of the previously core biopsy, so that the entire malignancy can be removed.
Bleeding is the most common complication of this procedure. It is important that patients stop any medicines that can increase bleeding time (such as aspirin or other NSAIDs, coumadin, Plavix, etc.) at least 10 days in advance of the procedure. After the procedure, the patient is wrapped in a pressure dressing, which minimizes bruising. The procedure usually takes less than an hour.
Open Surgical Biopsy
In some cases, the core biopsy will be either non-diagnostic or may demonstrate the type of high-risk changes that require a more generous sampling of tissue. The decision to do an open surgical (or excisional) biopsy requires a coordinated discussion between the mammographer, the pathologist, the surgeon, and the patient.
In the case in which the area of concern is not palpable (i.e. not a lump that can be felt), the mammographer will usually place hook wires before the surgical biopsy is performed. This is done in the radiology department under local anesthesia. The mammographer places a hook wire in the middle or on either side of the area of concern. The wires allow the surgeon to locate this area based on the position of the wires. To make certain that the appropriate area has been removed, an x-ray is taken of the biopsy specimen after removal (while the wires are still present in the specimen).
In the case of a lump that the surgeon can feel, the open biopsy can be done without needle localization. In most of these cases, a needle biopsy is still done in advance so that an accurate removal and diagnosis can be made.