Boxers and pugs are more likely to have low grade tumors than other breeds. The grade of the tumor directly relates to the prognosis for your pet. The grade cannot be determined until it is removed surgically and evaluated using histopathology. This includes looking at a sample of the tumor under a microscope. Tumor grade is based on the invasion of the tumor into surrounding skin and other tissues, the number of actively dividing cells, abnormal cellular morphology, and the characteristics of the intracellular structures. The grade will dictate the metastatic potential (chance of tumor spread), long-term survival time, and necessary follow-up treatment options such as chemotherapy. Generally speaking, lower grade tumors have longer survival times and higher grade tumors have shorter survival times. Additional prognostic factors include breed, clinical presentation, tumor location, staging results, and surgical margins. Your pet’s ACVS board-certified surgeon will discuss these results with you to develop a specific treatment plan for your pet following surgery.
Genetic analysis of the tumor may also be recommended by your pet’s ACVS board-certified veterinary surgeon. This test is used to look for a certain cellular growth factor called KIT (CD117) or more commonly known as the C-Kit Mutation. The C-Kit mutation is an abnormality with a specific cellular receptor involved with proliferation and other biologic activities. This mutation is more common with higher grade tumors resulting in higher recurrence rates, increased cellular proliferation, and ultimately shorter survival times. This mutation is present in approximately 15–40% of mast cell tumors.
Feline Mast Cell Disease:
Feline mast cell disease is different from mast cell tumors found in canine patients. It accounts for 8-21% of skin tumors in cats. The most common feline breed associated with this disease is the Siamese cat. Unlike the dog, the most common locations found in feline patients are the head and neck followed by the extremities. Additionally, cutaneous mast cell tumors found on the head and neck of cats are less aggressive than those found in dogs. Some cutaneous mast cell tumors will spontaneously regress. However, if you notice a tumor on your cat it is recommended to schedule an appointment with your primary care veterinarian for evaluation. Cats with cutaneous mast cells still need clinical staging prior to surgery to evaluate for metastasis. The overall prognosis for cats with the cutaneous form of this disease is good with low recurrence rates. A more serious form of mast cell tumors exists in cats known as the visceral form where the intestines or spleen is affected without any tumors on the skin. Removal of the spleen should be pursued in these cases. This form carries a poor prognosis and is associated with clinical signs such as vomiting, weight loss, and loss of appetite.