Lumps and bumps in the skin are common findings in our canine and feline companions. Luckily, most of these are benign changes that represent superficial growths of the skin or fatty accumulations under the skin (lipomas). Unfortunately, cancerous growths in the skin can also occur. These are more common in older dogs, however cancer can also be found in young dogs and cats as well.
Any lump on your pet should be evaluated by your veterinarian. Some superficial growths can simply be monitored depending on their appearance. Growths that occur under the skin should be investigated further as many different types of tumors can have a very similar feel. Generally, lumps under the skin are first investigated by the least invasive technique possible, which is usually a procedure called a fine needle aspirate. This involves collecting a small number of cells using a needle and evaluating them on a slide. A needle aspirate does not require sedation or anesthesia for most pets and is not painful. If a benign growth is identified, monitoring is generally recommended unless it continues to grow or starts to bother the pet. A record of the size of the lump and its location should be kept for future comparison. Any lump that grows or changes should be re-evaluated even if it was previously determined to be benign.
If a lump is highly suspicious for cancer and a definitive diagnosis is not obtained via a needle aspirate, a biopsy is generally recommended. Biopsies can sometimes be done with a local anesthetic, however in most circumstances a short general anesthesia is required. A biopsy involves obtaining a piece of tissue for evaluation. This can be done by obtaining a small portion of the lump (incisional biopsy) or by removing the entire visible lump (excisional biopsy). The most appropriate type of biopsy is determined by your veterinarian.
If a cancerous growth is identified by either needle aspirate or biopsy, the best course of treatment depends on the type of tumor, the grade of the tumor, as well as the stage of the disease. The grade of a tumor is used to describe how aggressive the tumor appears microscopically and can generally only be determined with a biopsy. Stage refers to whether or not a tumor has spread to other areas of the body. Staging tests to look for evidence of tumor spread may include blood work, a lymph node aspirate, chest radiographs, abdominal ultrasound, and in some instances a whole body CT scan. If no evidence of tumor spread is found, the initial treatment of choice for cancer of the skin is surgery. Most cancers of the skin are locally invasive. This means that cancer cells extend microscopically beyond the visible mass into the surrounding tissue. Wide surgery is planned to attempt to remove all of the visible mass as well as the microscopic extensions. Once a mass is removed, the entire tissue is submitted for evaluation (biopsy). The purpose of the biopsy is to confirm a diagnosis, obtain a grade (if not already known), evaluate for prognostic features, and determine whether all of the tumor was removed successfully.
Additional therapy after surgery is sometimes recommended depending on the final biopsy results. For tumors that cannot be completely removed with surgery (microscopic disease remains), there is high risk for local recurrence and radiation therapy may be recommended. Radiation is a local therapy that is used with the goal of killing any remaining cancer cells left at the surgery site and preventing them from regrowing. Chemotherapy may be recommended for tumors that have a high chance of spreading to other areas of the body, when pre-existing cancer spread is found, or if surgery is not a feasible option due to size or number of tumors.
Here at the Las Vegas Veterinary Specialty Center, we have a dedicated Oncology department with two board certified veterinary Oncologists. We have the staff and resources to give your pet the best care possible, and work with your family veterinarian to craft a treatment plan that is ideal for you and your pet.