A mass is an extremely common finding in daily practice, yet it often presents a challenge. Should it be ignored? Should it be tested? Should it be removed? Should it be removed when it gets larger? Should we “just watch it”? Should the client “keep an eye on it”? What is the standard of care?
Relying on your ability to “diagnose” a mass by visualization or palpation alone is risky at best. After all, the mast cell tumor is nicknamed “the great imitator” for a reason… Oral masses and the poorly named “epulis” can be notoriously misleading.
The fact is, we don’t have universally approved guidelines for handling masses. (One exception might be a white paper by Barb Biller et al: 2016 AAHA Oncology Guidelines for Dogs and Cats.) In addition, financial, emotional, and practical concerns make the decision-making process more difficult.
For starters, we don’t have objective criteria to decide between observation and intervention: What is an acceptable size or what is an adequate duration for a mass to be present before we act on it? We don’t have a foolproof way to determine if a patient is bothered by a mass until it’s obvious. Size does not matter when it comes to masses. Even a tumor the size of a grain of rice on a very small patient can quickly turn into a nightmare to remove or require a very invasive surgery, for example, when it is located on an extremity or the gum. Not to mention an excision with wide margins may require sacrificing an entire body part, such as a limb.
Since we don’t have objective criteria, we need to rely on common sense, experience, and surgical wisdom to make decisions.
In all cases, it is critical to thoroughly document your findings in the medical record. Keep in mind notes are meant to be read at a future date by you, another general practitioner, a specialist, or, who knows, your friendly veterinary medical board.
At a minimum, your notes should include:
- Recent and relevant history, including duration and size changes
- A “patient map,” similar to what you use on a biopsy request form or a dental chart, so you can localize the precise location of masses. This allows you to avoid needlessly re-aspirating previously evaluated masses or missing new ones, thinking they have already been checked
- The size of any mass in three dimensions
- Which layers of tissue appear to be involved
- Whether the mass is easily movable or attached to deeper structures
- Its color and feel
- Whether the patient experiences discomfort upon palpation
- Ulceration or drainage
Consider the following example of a note: “One month history of a soft, SQ, grape-sized, easily movable, quickly growing, non-painful mass on the cranial aspect of the right carpus.”
There are three main ways to reach a diagnosis: a fine-needle aspirate (FNA), a biopsy, and excision.
The fine-needle aspirate
At a minimum, any mass, regardless of size or duration, should be evaluated. An FNA is an inexpensive, noninvasive way to start the diagnostic process. It should be performed with a 22-gauge needle. If at all possible, make multiple slides. Unless you are absolutely confident in your ability to read microscopic slides, it is safest to have a board-certified pathologist read the results. As the saying goes, “When in doubt, send it out.”
An FNA often provides you with an idea of what you are dealing with. Giving your pathologist the appropriate amount of information is important. Include any pertinent details, such as patient history and diagnostic findings (blood work, radiographs). Evaluation and or sampling of the surrounding lymph nodes should also be considered. Studies have shown palpation is not a reliable indicator of diagnosis.
When the FNA report shows a mass is benign—assuming you trust it—the result can still be helpful. More often than not, it can help rule out the presence of exfoliating tumors, such as a mast cell tumor. A benign diagnosis also means a less invasive surgery will be required since we don’t need wide margins.
If the FNA doesn’t provide you with enough information to proceed, obtaining a biopsy is the next option. In some cases, it may be wise to skip the FNA and go straight to a biopsy. There are multiple types of incisional biopsies, including core, wedge, and punch. Always remember the formalin-to-tissue ratio should always be 10:1 to allow proper fixation.
A biopsy may be a tough sell to an owner if finances, sedation, or anesthesia are a concern. However, it can provide critical information about the grade of a tumor. This can affect the surgical approach, including the extent of margins and adjuvant therapies.
Send the history to the pathologist. If the cells are not straightforward, the more information provided to the pathologist, the more likely he or she is to give a definitive answer, or at least narrow it down.
Ideally, every mass that is removed should be sent out for histopathology. The biopsy report will shed some light on the diagnosis, the grade of a tumor, and the width of its margins.
Send the entire tumor when possible. This may require using multiple jars. Make sure you are familiar with your lab’s protocol for evaluating margins. Identify areas you are concerned about with ink, sutures, etc. Don’t be afraid to communicate with your pathologist if something is unclear or if you feel part of the information you need to properly treat the patient is missing.
Ultimately, very few masses regress spontaneously. Early diagnostics and proactive excision typically means a shorter anesthesia, a less invasive surgery, and a smaller invoice. What’s not to like about this win-win situation?
|AN ONCOLOGIST’S OPINION|
|Sue Ettinger, a board-certified oncologist in Norwalk, Conn., is on a mission to raise cancer awareness in dogs and cats. She encourages practitioners to document masses on a skin map. (You can find examples here: drsuecancervet.com/skin-maps.)
Her campaign, “See Something, Do Something. Why Wait? Aspirate” has a simple goal: diagnose cancer earlier so you can treat it earlier. “See something” means that when a skin mass is the size of pea or larger, or has been present for one month, you should “do something,” meaning aspirate or biopsy. The results will then guide the treatment options. Ultimately, procrastination rarely helps the patient. Early detection saves lives.
Phil Zeltzman, DVM, DACVS, CVJ, Fear Free Certified, is a board-certified veterinary surgeon and author whose traveling surgery practice takes him all over Eastern Pennsylvania and Western New Jersey. You can visit his website at www.DrPhilZeltzman.com. He also is cofounder of Veterinary Financial Summit, an online community and conference dedicated to personal and practice finance (www.vetfinancialsummit.com). AJ Debiasse, a technician in Stroudsburg, Pa., contributed to this article.