Basal Cell Tumor in Cats

Middle-aged and older cats develop basal cell tumors more commonly than young cats. The tumors can occur anywhere on the body, and are often pigmented. If a basal cell tumor is malignant (cancerous), ulceration and infection of the tumor is possible. Even when cancer is present, metastasizing (spreading) is rare. These tumors are found more often in long-haired breeds of cats. Veterinary treatment is very effective at relieving this condition and should be sought as soon as possible.

When an abnormal growth of skin cells occurs on the outer layer of the epidermis, it is referred to as a basal cell tumor. These tumors show up as firm bumps which sometimes grow out on a stalk and tend to be anywhere from 1-10cm in diameter. The growth of basal cell tumors is slow. If other benign tumors are present, these tumors will merge into them. They also sometimes form in sebaceous sweat glands. Basal cell tumors are the most commonly seen type of tumor in cats.

You may notice basal cell tumors while petting or grooming your cat. The presence of any abnormal bump merits a veterinary assessment. Symptoms are as follows:

• Solitary, firm bumps
• Hairless bumps
• Pigmented bumps
• Ulcerated spots occurring on the head, legs or neck
• Hairless skin patches
• Rashes
• Open sores that will not heal

The exact cause of basal tumors is not fully understood. The same tumors develop in humans from too much sun exposure, however, the sun's rays are not proven to have the same effects in cats. All possible causes are listed below:

• UVA/UVB exposure
• Genetic predisposition (especially in the Himalayan, Siamese and Persian cat breeds)
• Chemical carcinogens
• Viruses
• Hormonal factors

To confirm the presence of a basal cell tumor, a veterinarian will need the cat’s full medical history. A physical exam will be completed, and a basic visual evaluation of the tumor can identify it as a basal cell tumor. The tumor will have to be differentiated from other inflammatory diseases that manifest similar symptoms. If the cat is a long-haired breed, that will also increase the likeliness of basal cell tumor presence. 

To complete the diagnosis, a microscopic examination is necessary. Tissue of the tumor can be collected by a punch or tissue biopsy, needle aspiration, or surgical excision (full removal). The tumor tissue will then be sent to a specialized lab where further testing can be done by a cytology (free tissue examination) expert or a histopathology (tissue on glass slides) expert. These microscopic examinations can pinpoint if the tumor is malignant or not, and if it is they can specify the stage, grade, type and behavior of the cancer cells. 

The best option for treatment depends on the type of tumor present, its size, and its location on the body. Even if malignant, basal cell tumors respond to treatment very well.

Surgical Removal 

For most basal cell tumors, the treatment method with the best success is the surgical removal of the tumor. This surgery is generally not very expensive. It also is not overly invasive, as basal cell tumors are on the outer layers of the skin. Some cases only require a partial removal of the tumor. General anesthesia is used for the surgery. 

Radiation and Chemotherapy 

These treatment options are usually paired with the surgical removal of a malignant basal cell tumor. Both of these options work to destroy cancer cells on a microscopic level. Radiation requires regular scheduled administration by a veterinary professional. Chemotherapy can sometimes be prescribed for a longer duration of time. 

Cryosurgery 

If the tumor is small enough, it may be possible to freeze it off with liquid nitrogen. This treatment is less invasive than actual surgery and can be just as effective in treating minor tumors. 

Antibiotics

If the tumor has become infected due to ulceration, or if the cat has undergone surgery, antibiotics may be prescribed to treat or prevent infection. These prescriptions generally last between 2-4 weeks.

Monitoring

If the basal cell tumor is benign and contains no ulceration, treatment may not be recommended. Regular monitoring may be the better option for a cat with benign tumors that do not impact the body negatively. 

If the cat has had a surgical removal of a basal cell tumor, it is very important to keep the operation site clean. The cat must not lick, scratch, rub or bite the incision. Activity should be limited during the healing process. Watch for any swelling or bleeding and return the cat to the veterinarian immediately if they do occur.

Prognosis depends on the type of basal cell tumor that is present, however even more aggressive carcinomas tend to develop relatively slow when compared with other cancers. As cancerous basal cell tumors tend not to spread through the body, a complete surgical removal is an  extremely effective treatment. If the surgery was incomplete due to tumor location, tumors can regrow. Most cats make a full recovery after benign or malignant basal cell tumor removal.