Biopsies are tissue samples taken for diagnostic purposes. They can be used either to determine the cause of an abnormality that shows up on a mammogram but is too small to feel, or to ascertain the nature of a lump or lesion that is large enough to be felt. If you have had a previous baseline mammogram, the trouble spots can be compared to the earlier image.

Changes that show up on mammograms include deposits of calcium in the breast tissue. Sometimes these calcifications indicate that cells are rapidly dividing (as cancer cells do). Although 80 percent of the calcifications that show up on mammograms are benign, any new cluster needs to be evaluated.

If a change shows up through physical examination of the breast (for example, a new lump, asymmetry, or an unusual density in the breast), sometimes further mammographic views, perhaps from different angles, will clarify the problem. If these additional views do not explain the nature of the change, or if the change or lesion is still worrisome, then we try a biopsy. Depending on the kinds of changes, different kinds of biopsies can be taken.

One kind of biopsy, called a stereotactic biopsy, is a needle procedure that uses computerized technology to take small samples of tissues for purposes of diagnosis. The mammographic x-ray machine serves as a basis for finding the tissues that need to be sampled but are too small to be felt. Stereotactic biopsies are usually performed by radiologists.

Another kind of biopsy, a minor surgical procedure, is called a needle localization biopsy. It is done either because the woman prefers not to have a mammographically localized biopsy, or because the location or character of the lesion rules out that procedure. This kind of biopsy is usually an outpatient procedure, often done in the x-ray department of a hospital. It involves removing the entire area of concern, not just taking needle-size samples of the tissue from that area.

The breast is anesthetized and a guide needle is inserted into the area to be biopsied. Once the guide needle is in place, the patient is taken to the operating room and given a mild intravenous sedative so that she feels no pain and is not frightened during the procedure. The surgeon then puts some Novocain into the location indicated by the guide needle and surgically removes the area of concern. Usually the incision is only about an inch and a half long. After the surgery there is only a little discomfort and not much deformity.

What kinds of biopsies are done for lumps or lesions that can be felt?

If there is a lump in the breast, a mammogram and an ultrasound can help determine its nature and find other lesions that may be too small to feel. A biopsy can be performed, if further investigation seems necessary.

One choice is a needle biopsy. The breast is anesthetized with a local anesthetic and a needle is inserted into the lump to sample a piece of the tissue. This sounds like an easy approach, but the surgeon must be very careful; since only a small sample is taken, there is a possibility that cancerous tissue is present but the needle has not hit it. The surgeon has to advise the patient whether to go a step further and have an excisional biopsy.

This excisional biopsy, also called an open surgical biopsy, is the second kind of biopsy. It is performed pretty much like a needle biopsy. The patient goes to the operating room and receives intravenous sedation. The breast is anesthetized with a local anesthetic and a small incision is made; the entire lump is removed. This procedure usually takes about an hour. There is not much pain afterward, not much deformity, little risk of infection — less than 2 percent — and an equally small risk of bleeding at the biopsy site.

An excisional biopsy is the best way to be absolutely sure of the nature of the lump. Sometimes a large lump may have a small bit of cancer inside. If the whole lump is removed and examined by a pathologist, we can be sure that we have not missed a cancer.

Which is better, a needle biopsy or a surgical biopsy?

My own preference is for an excisional biopsy. One of the worst things I can do for a woman is to have her undergo a needle biopsy, reassure her that her lump is benign, then discover six months or a year later that in fact the needle missed some cancer. If the test gave a false negative in this way, an easily cured tumor might have become more difficult to treat.

If a woman has a lump that looks cancerous to her examining physician, and its location and nature make it easy to sample with a needle, then it is wise to counsel the patient before surgery to avoid two procedures and proceed with the one that burdens her less. The needle biopsy can make the diagnosis immediately. Occasionally the surgeon will then recommend radiation therapy before surgical excision if the tumor is large.

Are biopsies safe during pregnancy?

Yes, they are safe during the second two trimesters of pregnancy — both to mother and to fetus. If a biopsy is needed during the first trimester, it is safe provided that it is done under local anesthesia.

What is the procedure if an ultrasound suggests that the lump is a cyst?

The treatment may be as simple as putting a needle into the cyst and draining the fluid. If the cyst goes away completely, your physician will schedule a follow-up visit in a month to be sure that fluid has not accumulated again. If the cyst does not disappear when it is drained, the area needs to be biopsied again — either with a needle biopsy or with an open surgical biopsy.

What can a pathologist tell about the tissue sample from a biopsy?

At a very basic level, a pathologist can tell whether tissue is benign or cancerous. The sample can also show the benign changes called atypical hyperplasia, in which the cells of breast tissue are growing too rapidly and some are not normal.

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