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Tests that can be done on lumps and bumps

November 2nd, 2016 Posted in Uncategorized


When a dog or cat comes to see me for a lump and I want to do some testing, I have a couple of choices. I can either do a Fine Needle Biopsy for a test called Cytology, or an Incisional (surgical) Biopsy for a test called Histopathology. Or I can do both tests.

What is the difference between these tests?

A Fine Needle Biopsy is taken using the same kind of needle we use to give an injection. Except that instead of injecting something into the lump, we are aspirating (sucking) cells out of the lump. We then squirt the cells onto a slide and examine them under the microscope.
With an incisional biopsy, a small piece of tissue is surgically removed from the lump. This can usually be done under sedation and a local, using a 4- 6 mm biopsy punch. The sample is placed in a jar of formalin to preserve it and it is shipped to a special laboratory. The lab sections the sample into fine slices and a pathologist examines the slices under the microscope.

What are the pros of a Fine Needle Biopsy? It is easy, inexpensive and the results are available relatively quickly.
What are the cons of a Fine Needle Biopsy? The sample can be very small, so sometimes there are not enough cells to make a diagnosis. Also, some tissues, such as those of connective tissue origin (bone cancers, sarcomas) have cells that are so tightly glued together that they cannot be aspirated. Other tissues, such as lymph nodes, have very fragile cells that break when they are aspirated. Finally, in some cases, the cells on cytology can trick us when inflammation is also present. In these situations, Histopathology is the better way to go, even if it is more expensive.

At Hespeler Animal Hospital we usually start with a Fine Needle Biopsy for the diagnosis of a lump. If we do not get the answers, then we recommend an incisional biopsy or simply removing the lump. Histopatholgy can then be run on that sample.

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