Managing Skin Growths in Dogs and Cats

Cutaneous and subcutaneous masses are very common in companion animal practice, and some veterinarians have become accustomed to monitoring growths that are small or slow growing and postponing surgery until the mass becomes larger. According to veterinary oncologist Sue Ettinger, DVM, DACVIM (Oncology) (also known as Dr. Sue Cancer Vet [DrSueCancerVet.com], however, this may not be the best approach. During presentations at CVC San Diego in December, Dr. Ettinger advised veterinarians to take a more progressive and proactive approach to managing skin growths.

See Something, Do Something

Dr. Ettinger promotes a cancer awareness program called “See Something. Do Something: Why Wait? Aspirate.” “See Something. Do Something” (SSDS) is a joint program with VCA that offers guidelines to promote earlier detection and intervention in managing skin masses. According to SSDS, if a skin growth has been present for 1 month and is 1 cm in diameter (about the size of a pea), it should be aspirated or biopsied. Dr. Ettinger notes that “in veterinary medicine, most skin and subcutaneous tumors can be cured with surgery alone if diagnosed early when tumors are small.”

Notes Dr. Ettinger, “The SSDS recommendations are helpful because definitive guidelines about when to aspirate or biopsy skin tumors in companion animals are lacking.” It is generally accepted that a rapidly growing skin mass that is changing in appearance, painful, or irritating to the patient should be addressed as soon as possible. But slow-growing tumors are not always held to the same standard.

Dr. Ettinger warns that long-term monitoring of these masses can allow them to progress and may require a more extensive or more invasive surgical procedure. It can also reduce the possibility of complete resection, increasing the likelihood of recurrence or the need for additional postoperative treatments. Dr. Ettinger notes that if small tumors are detected early, identified appropriately, and removed completely (ie, with clean surgical margins), further treatment is not required in most cases, improving long-term patient outcomes.

Early, presurgical diagnosis is an important component of SSDS. This can be accomplished either through fine-needle aspiration and cytology or through tissue biopsy.

Diagnostic Methods

Fine-Needle Aspiration and Cytology

Dr. Ettinger says fine-needle aspiration and cytology is advantageous because, compared with biopsy, it is minimally invasive, relatively inexpensive, and can be performed during a regular outpatient visit. It can help distinguish tumors from inflammation, and some tumor types, such as lipomas, are identified using this method. Cytology results are sometimes inconclusive, necessitating biopsy to obtain a definitive diagnosis. Clinicians are advised that any aspirate sample that does not consist exclusively of fat (lipo-ma), cyst fluid, or acellular debris should be submitted to a diagnostic lab for evaluation by a trained cytopathologist.

Biopsy

Dr. Ettinger says tissue biopsy can be used for initial tumor identification or to clarify an inconclusive cytology result. Performing a biopsy before tumor removal is recommended because it helps determine a treatment plan. Some veterinarians forgo presurgical biopsy of a skin mass and perform an excisional biopsy. This has the advantage of treating the problem (removing the tumor) and obtaining a diagnosis (via histopathology) at the same time.

However, Dr. Ettinger cautions that this approach is not ideal because recommended surgical margins vary among tumor types, so additional surgeries and/or follow-up radiation or chemotherapy may ultimately be required to treat the growth. Some malignant growths require 2- or 3-cm surgical margins, so forgoing a presurgical biopsy increases the likelihood of incomplete resection, which may necessitate additional surgeries or other follow-up treatments. “Re- search confirms that the first surgery is the patient’s best chance for a cure,” Dr. Ettinger says. “The goal of SSDS is that the first surgery is the only surgery for the patient.”

Treatment Planning and Tumor Recurrence

Under SSDS guidelines, once a tumor type has been confirmed, the optimal treatment can be explored. Dr. Ettinger cautions that not all benign tumors require surgical resection. If, perhaps due to location, removing the growth when it becomes larger would complicate complete removal, then early excision is recommended. Similarly, if a benign growth is bleeding or causing pain, infection, or irritation, surgery is recommended. Veterinarians may elect to monitor growths that would require extensive or complicated surgery to remove. However, SSDS guidelines recommend that the pet should be re-evaluated by the veterinarian every 3 to 6 months, and the mass should be measured each time, not merely visually assessed.

Dr. Ettinger also recommends that if biopsy or cytology confirms a malignancy, clinicians should consult a veterinary oncologist for staging and treatment recommendations.

Patients at risk for recurrence of skin growths can also benefit from SSDS recommendations. In these patients, pet owners and veterinarians both have important roles:

• Pet owners should check their pets each month, noting the size and location of any growths.

• Evaluate all growths via fine-needle aspirate and cytology.

• Biopsy can be performed if cytology results are inconclusive.

Facilitating early detection of regrowth or metastasis can increase the chance of a better outcome.

Summary

Whether dealing with a new growth or a recurrent one, Dr. Ettinger advises a proactive approach to skin tumors, as early detection and intervention can save lives.