Ear Canal Tumors

What are ear canal tumors?

Ear canal tumors are abnormal growths that can develop from any part of the ear canal, including the skin, the glands that produce earwax and oil, or the underlying connective tissues, muscles, and bones.

Benign tumors do not spread, while malignant (cancerous) tumors can spread to the surrounding tissues or other parts of the body (a process called metastasis). Tumors of the external ear canal are more common than middle or inner ear tumors.

• The most common external ear canal tumors in dogs are ceruminous gland adenomas (benign) and adenocarcinomas (malignant). Other tumors include inflammatory polyps, papillomas, and sebaceous gland adenomas. 
• The most common external ear canal tumors in cats are nasopharyngeal polyps, squamous cell carcinomas, and ceruminous gland adenocarcinomas.
• Lymphoma, fibrosarcoma, and squamous cell carcinomas are occasionally seen in dogs’ and cats’ middle or inner ears.

What causes ear canal tumors?

Why a particular pet may develop this, or any other tumor or cancer, is not straightforward. Very few tumors and cancers have a single known cause. Most seem to be caused by a complex mix of environmental and genetic factors. 

Although there does not appear to be a genetic or hereditary cause for ear canal tumors, chronic inflammation is believed to play a role. For example, German Shepherds and Cocker Spaniels are at increased risk of developing these tumors, possibly because both breeds are prone to recurrent and severe ear infections.

What are the signs of ear canal tumors?

Initially, these tumors may appear as one or more pink, white, or purple nodular masses in the ear canal. If benign, they may grow to a certain size and may not cause problems. If malignant, they may continue to grow, ulcerate (break open), bleed, and become infected, causing recurrent or chronic ear infections. They can narrow or completely obstruct the ear canal as they grow.

The most common signs of ear canal tumors include:

• An inflamed, itchy, and painful ear
• Persistent smelly discharge (can be waxy, pus-filled, or bloody)
• Head shaking
• Ear scratching
• Ear hematoma (blood blister) on the pinna (ear flap) if the pet shakes or scratches vigorously
• Draining abscesses just below the ear (occasionally)

If the middle or inner ear is involved, signs may include:

• Head tilt
• Circling
• Loss of balance and coordination
• Nystagmus (eyes darting back and forth)
• Horner’s syndrome (neurological condition with signs that include a droopy eyelid, smaller pupil, and sunken eye)
• Facial paralysis (with facial drooping, excessive salivation, and difficulty eating)
• Hearing loss
• Other neurologic signs

How are ear canal tumors diagnosed?

Ear canal tumors can be difficult to see if they are located deep within the ear canal. If the ear canal is severely inflamed, your veterinarian may first need to reduce the inflammation before the mass can be seen clearly. Once the mass is identified, it may or may not be possible to collect a tissue sample, depending on its location. If the mass can be reached, your veterinarian may perform a fine needle aspiration (FNA) or biopsy. 

• FNA involves using a small needle and syringe to collect a sample of cells directly from the tumor. The cells are placed on a microscope slide, and a veterinary pathologist examines them under a microscope.
• A biopsy involves surgically removing a small piece of the tumor. The tissue sample is then examined under a microscope, a process called histopathology.If the tumor is found to be malignant, a CT scan of the head and neck may be performed to determine how far the tumor extends and to help plan surgery. 

Staging (searching for spread to other parts of the body) is highly recommended for malignant tumors. This may include bloodwork, urinalysis, radiographs (X-rays) of the lungs, and an abdominal ultrasound. If any lymph nodes are enlarged or firmer than normal, samples may be taken to look for spread.

How do ear canal tumors typically progress?

Benign tumors, such as inflammatory polyps, typically grow only to a certain size but are often irritating and may interfere with the ear’s normal function, resulting in wax buildup and chronic infections. 

Local invasion of nearby tissues is often the biggest concern with malignant tumors (other than the possibility of metastasis). If the tumor is not treated, it may continue to grow and invade surrounding tissues, causing pain and increasing the risk of the more serious signs and complications listed above.

How are ear canal tumors treated?

Treatment usually involves surgery to remove the tumor. In many cases, complete removal of a benign tumor resolves the problem. Laser surgery may be an option in some cases. More extensive surgery is typically needed for malignant tumors. One procedure, called total ear canal ablation and bulla osteotomy (TECA-BO), involves removing the entire ear canal and the tympanic bulla (middle ear), leaving the ear flap in place.

If the tumor cannot be completely removed, radiation therapy may be recommended to destroy any remaining tumor cells. Radiation therapy may also be used for large tumors that cannot be surgically removed to slow tumor growth or relieve pain. Chemotherapy may be recommended if the tumor is highly malignant or if there is evidence that it has spread to other parts of the body.

Is there anything else I should know?

It is important to recognize that ear canal tumors may grow with few obvious signs at first. Regular examinations and rechecks with your veterinarian may help detect these tumors earlier and improve treatment options.