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Ask The Vet: I've found a new bump on my pet: Now What? by Stefanie Wong, DVM
October 29, 2018

It is bound to happen... you're petting and loving on your furry companion and you feel something new.  Your fingers move over a raised bump that you've never felt before.  The question arises - is this something I should be worried about?

With new bumps, or masses as we call them, there are always two possibilities - they could be benign - in which case, often treatment is not needed, or they could be malignant or cancerous.  There are a few different ways to make this determination.

With each new mass, we will ask you a few questions during the appointment:  When did you first notice it?  Has it grown in size or changed in any way (color, shape)?  Does your pet seem to be bothering at it or trying to get to it?

It is best to get any new masses checked by a veterinarian, especially because they are going to be easier to address when they're small vs. if they've been allowed to grow.  Sometimes all we need to do is a visual inspection and physical palpation.  More often than not though, we will recommend further investigation.

The first step is to do a needle biopsy, also known as a Fine Needle Aspirate (FNA).  We often start with the FNA because it is minimally invasive, does not require sedation and is less expensive than other techniques.  While it can often give us an answer in terms of what we are dealing with, it is possible that this step may come back inconclusive.  There are some masses that do not give us enough cells to get a diagnosis (we call them "non-exfoliative").  In some cases, a larger piece of the tissue must be obtained in order to get an answer.

If the FNA does not give us our answer, then the next step is to perform a biopsy.  Biopsies will need to be done under sedation or anesthesia.  With a biopsy, we have a much greater chance of getting a definitive diagnosis.  There are two different types of biopsies - incisional and excisional.

-Incisional biopsy means we take a piece or section of the mass, but do not remove the entire thing.  This is most often done with a punch biopsy, which looks like a small cookie cutter.  The biopsy site is closed with a few stitches.  The biopsy will be sent out for analysis to a pathologist.

-Excisional biopsy means we remove the entire mass.  Often this will be performed as a surgery under general anesthesia.  The mass and surrounding tissues will be sent out for analysis to a pathologist.

There are reasons for choosing one technique over the other.  We will often recommend an incisional biopsy if the mass is extremely large and we think surgery may not be an option or if the mass is located in a location where surgery would be challenging.  Doing a biopsy prior to surgery allows for surgical planning.  It allows us to know how large of margins we need to take when performing surgery and also it allows us to set your expectations and give you an idea of prognosis.

We will recommend an excisional biopsy if the mass is small, if it's in a location amenable to surgery with wide margins or if we have an owner who would prefer to have it all done (removing and obtaining a diagnosis) under one procedure.

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