What is Basal Cell Tumor?
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.
Symptoms of Basal Cell 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
- Open sores that will not heal
Causes of Basal Cell Tumor in Cats
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
- Hormonal factors
Diagnosis of Basal Cell Tumor in Cats
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.
Treatment of Basal Cell Tumor in Cats
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.
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.
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.
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.
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.
Recovery of Basal Cell Tumor in Cats
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.
Basal Cell Tumor Questions and Advice from Veterinary Professionals
My 17 yr old male had a malignant basal cell tumor removed from behind the ear 18 months ago. It has grown back to about 1" in diameter in the past 18 months and somewhat more rapidly over the last couple of months. It has not ulcerated and the skin is in good condition but it's quite uncomfortable, especially when he must scratch behind his ear...it hurts quite a bit. My vet is not anxious to remove it until it really starts to impact quality of life as he's quite sure that it will grow back, and likely even faster meaning yet another surgery to remove it would be necessary to maintain quality of like. But i don't want it to become so large that all bets are then off. Until the tumor starting becoming uncomfortable, he was an active, healthy, senior cat. I'm very torn and want to know if there are medications that can shrink such a tumor. I've read that radiation therapy could possible help to shrink it but it's quite involved, sedation is necessary, and must be done multiple times. I don't know what is the least egregious approach.
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Tumor on left proximal toe.
Received: 2.7 cm amputated digit.
Mass, left proximal digit
Multiple sections of digit are examined including soft tissue, nailbed region and phalangeal bone. The submitted digit contains an ulcerated and aggressive malignant mass. The mass is composed of malignant invasive cords, nests and lobules of basaloid epithelial cells surrounded by a scirrhous stromal response. Individual epithelial
cells have large rounded nuclei, prominent nucleoli and generally moderate amounts of eosinophilic cytoplasm. Occasionally within solidly cellular lobules, vague tubular and ductular type
differentiation is seen characterized by a few probable indistinct tubules lined by more cuboidal epithelium. Mitotic index is high at
13 mitotic figures per 10 high power field (400 X). A few lymphatics contain neoplastic emboli.
Basaloid carcinoma, invasive, poorly differentiated with lymphatic invasion
Histologic features most support a poorly differentiated basaloid carcinoma arising from basaloid epidermal or potentially adnexal epithelium. The mass may represent of poorly differentiated basaloid apocrine ductular carcinoma which can have a more solidly cellular histologic pattern. This cutaneous carcinoma appears aggressive and lymphatic invasion is identified. The mass is considered to have distinct potential for recurrent growth as well as regional and
distant metastatic spread. Although complete surgical resection potentially can be curative, the prognosis for this tumor remains guarded.
The proximal soft tissue and bone margins are clean.
Kristine Krotec VMD, Diplomate ACVP
I am available during regular business hours (Eastern Time Zone), Thursday-Sunday. Veterinarians, if you would like to discuss this case please email me at [email protected] or call my direct number at 410-527-0142. If I am unavailable, please call Customer Service at 1-800-745-4725 (ANTECH WEST) or 1-800-872-1001 (ANTECH EAST).
Note: With our Antech OnLine viewer, you can access the pathologist`s Snippet image of the histopathologic lesions of this accession. Open the accession on Antech OnLine, and click the large DigiPath icon. You will see Antech Diagnostic`s exclusive interactive Snippet,
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My 10 year old male cat was just diagnosed with a basal cell carcinoma. The mass is marble sized and located on the muscle behind his right knee. My veterinarian is recommending amputation as the best option because of the location. My cat is in pain and limping.
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Hi my cat has a bump located on his back, I would say half way between his collar bone and tail. It is a pinkish color, maybe the size of a small round pill. It does not seem to bother him when I touch it, and when I do, it feels as if it moves. Yesterday I noticed it was a little scabby, and some of the scab had fallen off. He is almost 11, no other symptoms, eats well and has great litter box manners. I have a photo of it if needed.
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