If your cat ever has a suspicious lump, bump, or mass that cant be diagnosed just by looking or touching, a biopsy may be ordered. Biopsy refers to any of several procedures for getting a sample of cells from a disordered area to allow microscopic inspection to help establish an accurate diagnosis. While there are many diseases that may require a biopsy, including liver abnormalities, certain gastrointestinal abnormalities, lung problems such as infectious or inflammatory conditions, mouth ulcers, and skin conditions, one of the most common times a biopsy is ordered is when cancer is suspected.
By obtaining an accurate diagnosis with a biopsy, the veterinarian can then determine the appropriate treatment type and course. The cats human also benefits from knowing the diagnosis, especially if the decision to provide treatment is based on knowing the tumor type and probable prognosis.
Obtaining the sample
There are three basic ways to perform a biopsy, says Rodney Page, DVM, director of the Comparative Cancer Program at the Cornell University College of Veterinary Medicine, who explains that the procedure to be used is determined by the site of the mass and the health of the cat.
The simplest method is a fine needle aspiration, which is used for lumps located near the skin. Here, a small needle on a syringe is inserted into the center of the bump or mass, and a minuscule quantity of the lump is sucked out for examination.
Needle aspirations present negligible physical risks to cats, cause little discomfort, and do not require the cat be sedated or anesthetized. In addition, recovery time is minimal. The largest risk of a fine needle aspiration, says Page, is failure to get an answer or a definitive diagnosis. This happens because aspirates sample, at best, a thousand cells at a time – so small a sample that it may fail to capture enough tissue to show whats occurring in the affected area.
When an aspirate falls short of diagnosis or when more information is needed to plan the treatment, the next biopsy option is to remove a small piece of the suspicious area in a technique called a core biopsy. Short-acting local anesthesia or sedation is given, and a tiny cylinder of tissue a centimeter long is cut with a narrow coring instrument. If the area to be sampled is in an internal cavity, the biopsy may be obtained via a laparoscope that has an alligator-like snip at its end.
Coring or snipping a sample yields a piece that contains about a billion cells of tissue. This gives the pathologist much more to examine than does an aspirate and is unlikely to fail in obtaining a critical tissue population.
The third option for biopsies is through an incision and thus is known as an incision biopsy. Here, a scalpel cuts a small wedge of tissue sample. With superficial lumps, the procedure is similar to coring. For those located deep inside the body, surgery is required. A veterinarian opens the cats abdomen, removes a tiny wedge of tissue, and sutures the internal site and the abdominal wound.
If cancer is a possibility, and the mass is small (less than 2 cm) we may attempt to remove the entire suspicious mass prior to diagnosis, explains Page. However, any masses that are large or firmly attached should be biopsied in order to guide the treatment plan. The risk to your cat from an incision biopsy is very slightly greater than in the other biopsy methods because as with all surgical procedures general anesthesia is used.
The pathologists report
Regardless of the type of biopsy performed, the sample is sent to a pathologist for laboratory examination to determine the disease; laboratory interpretations typically take several days or longer.
The pathologist will identify the mass, will detect whether it is benign or malignant (cancer), and will help determine how advanced the disease is.
Although biopsies are not foolproof and misinterpretations do happen, the biopsy is one of the most important steps in managing disease and determining outcome, says Page.
A cat may need medication for pain relief after exploratory surgery but usually for a much shorter time than humans need after a similar procedure. Remarkably, cats recover far more quickly than do humans. Typically, they are up and walking the next day.