Fine needle aspirates to diagnose dog cancer?
ByHi everyone,
I have been getting questions about the best way to gather info about growths in dogs. So, let’s take a look at a common technique used to accomplish this…a fine needle aspirate.
First of all, a fine needle aspirate is not a biopsy. A fine needle aspirate is a sample of the mass taken with a skinny little needle (meaning, not much to work with). The vet will disinfect the surface of the site to be aspirated, often after clipping the hair, to prevent infection. Next, a needle is introduced into the area of interest, and the plunger drawn back, creating a vacuum which draws cells into the hub of the needle. These cells are then used to make a slide for the vet or a pathologist to look at for a diagnosis.
What is good about this technique? Well, it takes about 2 minutes to do, and your dog gets to go home without sedation, anesthesia, or hospital stay. Quick, easy, outpatient…nice. This is a good technique to diagnose TYPE of growth (in my hands about 75% of the time you get this info from the path lab after submitting the slide).
How about downsides? A fine needle aspirate cannot tell if the cancer cells have moved inside the body or spread into neighboring areas. There is a little inaccuracy in this technique as well. My experience is that about 1 out of 4 of these come back “inconclusive”, meaning there was not enough on the slide for the path folks to give a diagnosis. Sometimes the vet will get a big sample, but the cells are just not the right kind to make a diagnosis (blood, connective tissue, etc.). Some tumors have a good cell yield, and others do not. Occasionally, we get an incorrect diagnosis with a fine needle aspirate.
Some dog tumors easily diagnosed with fine needle aspirates:
Lymphosarcoma/Lymphoma
Mast Cell Tumors
Histiocytomas
Lipoma
Cysts
Short story, this technique is a good, non-invasive, rough screen to get initial information. Just keep in mind the limitations…it is not guaranteed and if there is any doubt in your vet’s mind, go for the real biopsy…coming up!
Best,
Dr Dressler
About the Author
Dr. Demian Dressler, DVM is known as the "dog cancer vet" and is author of Dog Cancer Survival Guide: Beyond Surgery, Chemotherapy & Radiation. Visit his blog and sign up free to get the latest information about canine cancer. Go to http://DogCancerBlog.com.
5 Comments
September 8th, 2008 at 11:42 am
Keep up your informative topics/threads Dr. Dressler!
Would fine needle aspiration give any info on sebaceous cysts? Not looking for cancer (or possibly) but any benefits to that?
Lori
September 9th, 2008 at 2:53 pm
Hi Lori!
Yes, you can get a presumptive diagnosis of a sebaceous cyst. Usually you need to use the physical exam findings along with the info in the path report (or that the vet gets with an in-house slide examination of the aspirated contents). With these two bits of info (the appearance, shape and feel on the physical, and the microscopic appearance of the cyst contents), you can be pretty sure of the diagnosis. Sebaceous cysts produce a typical material within them that is pretty consistent.
Why bother with an aspirate of a suspected cyst? Well, one example is a situation you are very familiar with: mast cell tumors, the Great Imitators. You have a firm, spherical nodule within dog skin on physical. Is is a cyst?? Well, maybe. Could be other things too on occasion. So it becomes a probability game…how safe are we if say (I base this number on my personal clinical impression only…) 80% of masses with this appearance on an exam actually are sebaceous cysts. This means that sometimes these lumps are NOT, and just FEEL like they are.
I always recommend the safest option: get it checked out. That way we are safe not just for the 80% that are confirmed, but also for the 20% that are actually something totally different. This means that one in five are not. For every 5 dogs that come along, one of ‘em will have something possibly harmful. Since I see gobs of dogs, the 20% WILL walk into my exam room and I WILL have to deal with it. So I always recommend the safest options.
Good blog topic! Thanks!
Dr Dressler
March 24th, 2009 at 3:45 pm
how much does something like this cost?
May 13th, 2009 at 1:14 pm
fine needle aspiration cost $20 today in Vancouver BC,
and the pathology lab cost $75, total with tax about $100.
most of what was extracted was fluid. lab analysis
results will come back in about three days.
June 7th, 2009 at 3:29 pm
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