A number of skin tumors can occur in cats, and most owners will find unexplained lumps and bumps on their pet at some point during its life. While skin tumors can be harmless, sometimes they are malignant or proliferative and invasive and deserve prompt medical attention. A veterinarian is the best person to assess skin tumors and determine if a given bump is a benign pimple, cyst, skin tag or abscess, or if instead it is cancerous and much more serious. One of the most common initial procedures used to assess skin tumors is a fine needle aspirate. During this procedure, the veterinarian will gently insert a needle into the lump, pull back on the syringe stopper to draw out some of the fluid and cells inside the mass and then “squirt” the sample onto glass slides for microscopic examination. Other diagnostic procedures may be required as well.
Once the cause of a skin tumor has been diagnosed, the treatment options will depend on the type of tumor, its location and size, the cat’s clinical signs and the tumor’s degree of aggressiveness. There are several basic treatment options for skin tumors: waiting and watching; surgical excision; Laser ablation and/or cryotherapy (freezing of the affected tissue). Chemotherapy and radiation therapy may be included in the treatment protocol.
Uncomplicated benign skin tumors usually are easily identifiable microscopically using the fine needle aspirate diagnostic procedure described above. Often, these tumors do not require treatment, but they can be surgically removed for cosmetic reasons or if they seem to bother the cat. Many owners decide to have benign skin tumors removed because they do not like how they look or feel. The “wait and see” approach (called “clinical neglect”) is often recommended for cats with histiocytic mast cell tumors, which typically are benign and tend to resolve without treatment. However, most skin tumors in cats are aggressive or invasive and require prompt treatment.
Skin masses that are diagnosed as malignant (or are prone to becoming metastatic) are normally removed at the first opportunity. Aggressive surgical resection, with wide margins around the tumor site, is the treatment of choice for virtually all of these skin tumors. Some feline skin tumors, such as basal cell carcinomas, can be removed fairly easily because they normally do not spread outside their margins. More aggressive skin tumors, such as fibrosarcomas, may require lengthy surgical procedures which include the removal of a margin of healthy surrounding tissue. Amputation may be recommended for animals with affected limbs.
The removed tissue will be submitted for examination by a veterinary pathologist, so that the attending veterinarian can assess whether all of the tumor cells associated with the mass have successfully been removed. If it appears that malignant cells extend close to the surgical margins, a second surgery may be necessary. Radiographs (x-rays) may be recommended to determine whether malignant forms of cancer have spread to nearby lymph nodes or other areas, particularly the bone marrow and lungs. Blood tests may be recommended as well. In many cases, radiation, chemotherapy, laser ablation and/or cryotherapy will be used in addition to surgical resection to improve the success rate. Owners must recognize that malignant tumors can recur post-operatively, despite heroic efforts by the veterinary team. Regular rechecks are important.