So what is a biopsy and what do we do with it?
Biopsies are performed every day of the year in every city in the USA. They take place in a kind of gulag, where things happen largely out of sight. Just as, at any moment, someone is born somewhere in this country, so is a biopsy being performed in some doctor’s office, at least during daylight. The interval between the biopsy and its result is relatively short when measured against the life of a patient, but what happens during this period has potentially serious consequences from the point of view of an individual’s personal health.
A biopsy is a surgical procedure whereby tissue is removed from the body for microscopic analysis. The tissue thus obtained is a biopsy sample. The term “biopsy”, however, may be used for either the active process of taking the specimen (i.e. performing a biopsy) or to describe the biopsy itself, as in “let’s examine the biopsy”. In many cases, the sample does not include the entire abnormality, but is a representative portion of a larger lesion (area of disease). Therefore, if one wishes to obtain information about a swelling or lump, this can often be accomplished by removing only part of it. However, when the lesion is very small, the procedure may capture the entire area of interest in one swoop. Sometimes, for example, an entire prostate may show no evidence of the cancer that was originally diagnosed on the basis of a thin biopsy obtained through a needle. Similarly, a small tumor of the uterine cavity may occasionally be removed during the curettage, leaving no residual cancer in the excised uterus.
There is no universally accepted upper size limit for defining a specimen as a biopsy, but certain specimen types, such as whole organ resections are classified differently from tiny samples, and are handled separately. The person performing the biopsy may be a surgeon, an interventional radiologist, a gastroenterologist, a dermatologist or any one of a number of clinicians qualified to wield a scalpel or biopsy forceps.
In recent years, radiologic techniques have advanced to such a degree that biopsy specimens are being extracted in remarkably creative ways from all parts of the body. Through tubes inserted via the esophagus and into the small intestine under ultrasonic guidance, threads of tissue (or suspensions of cells) may be withdrawn from deeply submerged organs like the pancreas. Needles and biopsy forceps yield the minutest fragments from the air passages of the lungs, the upper reaches of the ureters, deep in the brain, or from the lymph node chain that runs along the spine. There is no place to hide from these instruments. As soon as the biopsy sample has been obtained, it must be presented to the pathologist in such a way that maximum benefit can be derived from its examination. In my opinion, a key part of the biopsy procedure occurs before the patient is even touched, namely the thinking and planning that should precede any incision.
It is obviously much easier to perform a biopsy at body sites within easy reach, such as the skin, oral cavity, uterine cavity and cervix, and so on. A physician contemplating a biopsy does so within the context of a clinical history, physical examination, and perhaps the results of radiologic studies or other findings. Doing a biopsy follows a decision arising from an opinion based on the observations that the clinician has made. It is costly to sedate or anesthetize a patient in order to go on a deep-seated biopsy mission, the result of which may be an excruciatingly tiny piece of tissue upon which the pathologist is expected to render a result. Therefore, everything needs to be carefully thought out, and the prize, the secured sample, must be handled like gold.
Material destined for a surgical pathologist’s microscope is generally placed into formalin, which penetrates the tissue to “fix” it prior to further processing. Very small samples fix rapidly, within a few hours. Others, like colon resections (not considered biopsies), require much longer Time in fixative. If an infection is suspected, then at least some of the tissue must be submitted in the fresh, unfixed state for microbiologic culture. This is because microbes exposed to formalin will die, and cannot be grown and identified in the laboratory. In certain instances, molecular or chromosomal studies must be performed, for which fixed tissue, again, may be suboptimal. Examination by electron microscopy requires fixation in yet another type of fixative. Things that go wrong may result from failure to consult a pathologist about the most suitable medium in which to submit the tissue.