Mast Cell Tumor Removal

Bylined by Adelinda Manna

Bottom Line

Mast cell tumor removal is a common surgical procedure for dogs and cats designed to excise cancerous skin growths. Early and complete surgical removal, often with wide margins of healthy tissue, offers the best chance for a positive outcome and preventing the spread of these potentially aggressive tumors.

What the procedure involves

Mast cell tumor (MCT) removal, or excision, is a surgical procedure aimed at completely removing the cancerous growth along with a surrounding margin of healthy tissue to ensure all tumor cells are captured. Mast cell tumors are the most common type of skin tumor in dogs and the second most common in cats, affecting the skin and subcutaneous tissue. They get their name from mast cells, a type of immune cell that contains granules packed with substances like histamine. When these cells degranulate (release their contents), they can cause local inflammation, redness, and swelling, and sometimes even systemic issues.

Before surgery, your veterinarian may recommend medical management, including steroids, antihistamines, and histamine blockers, to reduce inflammation and related side effects of the tumor. The procedure itself begins with general anesthesia. The veterinary surgeon carefully marks the tumor and the necessary wide margins around it. These 'wide surgical margins' are crucial because mast cell tumors are known to invade surrounding tissues. The goal is to achieve 'clean margins,' meaning no tumor cells are found at the edges of the removed tissue when examined under a microscope later. This significantly reduces the chance of recurrence. Once the tumor and margins are removed, the area is carefully closed, sometimes requiring skin flaps, especially for larger excisions. The excised tissue is then sent to a pathology lab for histopathology, which confirms the tumor type, its grade (a key factor for prognosis), and evaluates the surgical margins. This microscopic analysis is vital for guiding any further treatment recommendations.

When this surgery is recommended

Surgical removal is typically the primary and most effective treatment recommended for mast cell tumors in pets, especially when they are localized to the skin or subcutaneous tissue. The decision to proceed with surgery is made after a thorough diagnostic workup, which often includes a fine needle aspirate (FNA) to confirm the presence of mast cells, and potentially staging tests like lymph node aspirates, abdominal ultrasound, and chest X-rays to check for metastasis (spread) to other organs. The grade of the tumor, which can only be determined after surgical removal and histopathology, is a critical factor in understanding the tumor's aggressiveness and guiding post-operative care.

Factors influencing the recommendation for surgery include the tumor's location, size, and whether it appears to be confined to the skin. While some benign skin growths might be monitored, mast cell tumors are considered malignant and require proactive treatment. Alternative approaches, such as radiation therapy or chemotherapy, are usually considered in conjunction with surgery for more aggressive tumors, those with incomplete margins after initial surgery, or those that have spread. For very aggressive or inoperable tumors, medical management may be the primary approach to improve comfort and slow progression. Your veterinary oncologist will discuss the best strategy, weighing the benefits of surgical excision against any potential risks or complications specific to your pet's health and the tumor's characteristics.

"Surgical removal of mast cell tumors is the preferred treatment once your pet is diagnosed with this disease. Mast cell tumors invade into surrounding tissues and wide surgical margins (wide area of healthy tissue surrounding the tumor Figure 2 and Figure 3) are necessary to ensure removal of all cancerous cells." -- ACVS, `https://www.acvs.org/small-animal/mast-cell-tumors/`

What it costs in the United States

The cost of mast cell tumor removal in the United States typically ranges from $1,500 to $6,500, reflecting the complexity of the surgery and associated care. This range can vary significantly based on several factors, including the size and location of the tumor, the need for advanced surgical techniques like skin flaps, and whether a board-certified veterinary surgeon performs the procedure. Geographic location also plays a role, with clinics in urban areas or those with a higher cost of living often charging more.

The overall cost includes several components. Pre-surgical blood work and diagnostics (like fine needle aspirates, potentially X-rays or ultrasound for staging) are necessary to assess your pet's health and the tumor's extent. The surgical fee covers anesthesia, the surgeon's time, surgical supplies, and facility use. Post-operative care, including pain medication, antibiotics, and bandage changes, also contributes to the total. A significant portion of the cost is for histopathology, the microscopic analysis of the removed tumor to confirm the diagnosis, determine the tumor grade, and evaluate surgical margins. If the margins are found to be 'dirty' (meaning tumor cells are at the edge of the removed tissue), further surgery or additional treatments like radiation might be recommended, adding to the overall expense. More complex cases, especially those requiring specialist care, tend to fall on the higher end of the spectrum.

Risks and contraindications

While mast cell tumor removal is a common and generally safe procedure, like any surgery, it carries potential risks and specific situations where it might not be the best course of action. Your veterinary team will carefully assess your pet's overall health and the tumor's characteristics to determine if surgery is appropriate.

Potential risks include complications from anesthesia, such as adverse reactions to medication or respiratory issues. Surgical risks can include bleeding, infection at the incision site, wound dehiscence (the incision opening up), or seroma formation (a pocket of fluid). Due to the nature of mast cell tumors, there's also a risk of degranulation during manipulation, which can lead to localized swelling, redness, and in rare cases, systemic effects like a sudden drop in blood pressure. Managing these risks involves careful pre-surgical planning, appropriate medication, and meticulous surgical technique.

Contraindications for mast cell tumor removal include:

• Active systemic mastocytosis with hemodynamic instability: If your pet is experiencing widespread mast cell release affecting vital signs, stabilization is crucial before considering surgery due to the high risk of severe degranulation.
• Significant comorbidity that contraindicates anesthesia: Underlying health issues, especially heart or kidney disease, might make the risks of general anesthesia too high. In such cases, biopsy and medical management might be a more appropriate and safer alternative.
• Inoperable tumors due to location or extensive spread: Tumors in very sensitive areas or those that have extensively spread (metastasized) throughout the body might be deemed inoperable. Staging tests are essential to determine the extent of spread, and surgery is typically only pursued after an oncology consultation if it's considered feasible and beneficial.
• Severe coagulopathy: Mast cell tumors can release heparin-like substances, which can affect blood clotting. If your pet has a pre-existing bleeding disorder, or if this effect is severe, it must be corrected and managed before excision to prevent excessive bleeding during and after surgery.

Recovery

Recovery from mast cell tumor removal typically involves careful wound management, pain control, and restricted activity for several weeks, with a full return to normal activity usually within 4-8 weeks. The exact timeline can vary depending on the tumor's size, location, and the complexity of the surgical repair. Your veterinary team will provide specific instructions tailored to your pet's needs.

What happens immediately after surgery?

Immediately after surgery, your pet will recover from anesthesia in the clinic. They will be monitored for pain, vital signs, and any signs of surgical complications. They will likely be sent home with pain medication and possibly antibiotics. The incision site will have sutures or staples and may be bandaged. It's crucial to prevent your pet from licking, chewing, or scratching the incision, often requiring an Elizabethan collar (E-collar) or a recovery suit.

What does the first week of recovery look like?

During the first week, focus on keeping the incision clean and dry. Administer all medications as prescribed. Activity should be strictly limited to short, leashed walks for potty breaks, avoiding running, jumping, or rough play. Check the incision daily for signs of redness, swelling, discharge, or separation. Your vet might schedule a recheck within a few days to ensure the wound is healing well.

What about weeks 2-4 and beyond?

Sutures or staples are typically removed around 10-14 days post-surgery, assuming the wound has healed properly. Continue to restrict activity until your vet gives the all-clear, usually around 3-4 weeks for simple excisions, and sometimes longer for larger or more complex repairs. Gradually reintroduce normal activity as directed by your vet. For some pets, particularly those with high-grade tumors or incomplete margins, follow-up treatments like radiation or chemotherapy may begin a few weeks after surgery. Lifelong monitoring for new lumps or recurrence is also important.

When to seek emergency care

While your pet recovers from mast cell tumor removal, it's vital to monitor them closely for any signs of complications or systemic issues that warrant immediate veterinary attention. Knowing what to look for and when to act can be crucial for your pet's well-being.

Seek immediate veterinary attention if you observe any of the following:

• A rapidly growing or sudden-appearance skin lump that changes size from day to day: This symptom, even if not immediately post-op, needs a same-week vet visit. Many MCTs fluctuate in size due to histamine release, and rapid changes can indicate an active tumor.
• A skin mass with redness, swelling, or ulceration: Any new or worsening redness, swelling, or an open sore (ulceration) around the surgical site or elsewhere on the skin warrants a same-week veterinary assessment. This could indicate infection, inflammation, or another tumor.
• A skin mass combined with vomiting, dark stools, or unexplained collapse: These are serious systemic signs that require immediate emergency assessment. They can indicate possible systemic mast cell release affecting internal organs, gastrointestinal ulceration, or other severe complications.
• Excessive bleeding or discharge from the incision site: A small amount of redness or clear discharge might be normal, but heavy bleeding or pus-like discharge needs immediate veterinary evaluation.
• Sudden lethargy, loss of appetite, or difficulty breathing: These could indicate an adverse reaction to medication, an infection, or other serious post-surgical complications.
• Chewing or licking at the incision site despite an E-collar: If your pet is managing to irritate the wound, it could lead to infection or dehiscence, requiring immediate intervention.

How to find a specialist

Finding a board-certified veterinary specialist, particularly a veterinary oncologist or surgeon, is highly recommended for mast cell tumor diagnosis and treatment to ensure your pet receives the most advanced and effective care. Board certification signifies extensive additional training, experience, and rigorous examination in a specific veterinary field.

Start by asking your primary care veterinarian for a referral. They often have relationships with specialists in your area. You can also use online directories provided by professional organizations like the American College of Veterinary Surgeons (ACVS) or the American College of Veterinary Internal Medicine (ACVIM), which certifies oncologists. These directories allow you to search for specialists by location.

When choosing a specialist, don't hesitate to ask questions. Inquire about their experience with mast cell tumors, their approach to staging and treatment, and what kind of support and follow-up care they offer. Ask about their communication style and how they will collaborate with your primary veterinarian. A good specialist will clearly explain the diagnosis, treatment options, potential outcomes, and costs involved. Look for a team that not only demonstrates expertise but also compassion and clear communication, as this journey can be emotionally challenging for pet owners. Selecting the right specialist can make a significant difference in your pet's outcome and your peace of mind.

"The grade of the tumor which determines the overall prognosis for your pet can only be evaluated after a surgical biopsy and histopathologic analysis of the tumor has been performed." -- ACVS, `https://www.acvs.org/small-animal/mast-cell-tumors/`

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