What are ear canal tumors?
Ear canal tumors are abnormal growths that can develop from any part of the ear canal (the skin, the glands of the skin that produce earwax and oil, and the underlying connective tissues, muscles, and bones). Ear canal tumors can be benign or malignant. Benign tumors do not spread, while malignant or cancerous tumors can spread to the surrounding tissues or other body areas (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, sebaceous gland adenomas, and more. 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 risk factors - some environmental and some genetic or hereditary. 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. This may be related to the tendency of both breeds to have recurrent and severe ear infections.
What are the clinical 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 or may not be problematic. If malignant, they may grow, ulcerate (break open) and bleed, and nearly always become infected, causing recurrent or chronic ear infections. They can narrow and even fill (and obstruct) the ear canal as they grow.
"If malignant, they may grow, ulcerate (break open) and bleed, and nearly always become infected, causing recurrent or chronic ear infections."
The most common clinical signs in pets with ear canal tumors include an inflamed, itchy, and painful ear, persistent smelly discharge (that can be waxy, pus-filled, or bloody), head shaking, and ear scratching. Sometimes pets will shake or scratch hard enough to cause an ear hematoma (a blood blister). Occasionally draining abscesses may form just below the ear. If the middle or inner ear is involved, pets may experience head tilt, circling, loss of balance and coordination, nystagmus (eyes darting back and forth), Horner’s syndrome, facial paralysis (with facial drooping, salivation, and difficulty eating), loss of hearing, and other neurologic signs.
How are ear canal tumors diagnosed?
These tumors may be challenging to see and diagnose if deep in the ear canal. If the ear canal is severely inflamed, the inflammation may need to be alleviated first to see the mass more clearly. Once the mass is identified, it may (or may not) be possible to take a tissue sample, depending on the location. Fine needle aspiration (FNA) or biopsy will be performed if the mass can be accessed. FNA involves taking a small needle with a syringe, suctioning a sample of cells directly from the tumor, and placing them on a microscope slide. A veterinary pathologist then examines the slide under a microscope. A biopsy is the surgical removal of a piece of the tumor. The tumor tissue is then examined under a microscope called histopathology.
If a diagnosis of malignancy is made from the FNA or biopsy, a CT scan of the head and neck region may be performed to determine how invasive the tumor is and plan a surgical approach. Staging (searching for potential spread to other locations in the body) is highly recommended for malignant tumors, as they tend to spread. 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 only grow to a certain size but are often irritating and interfere with the ear’s normal function, resulting in waxy buildup and chronic infections. Local spread is 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 the surrounding tissues, causing pain and increasing the risk of the more serious clinical signs and complications listed above.
How are ear canal tumors treated?
The treatment of choice for ear canal tumors is surgical excision. This is curative for benign tumors that are completely removed. Laser surgery may be an option. More extensive surgery is required for malignant ear canal tumors. One procedure, called total ear canal ablation and bulla osteotomy (TECA-BO), involves removing the outer and inner ear canal and the tympanic bulla (the middle ear), leaving only the ear flap remaining.
"The treatment of choice for ear canal tumors is surgical excision."
If complete removal of the tumor is not possible, radiation therapy may be recommended to treat the remaining tumor cells. Radiation therapy may also be recommended for large tumors that cannot be surgically removed to slow tumor growth or relieve pain. Chemotherapy may be an option if the tumor is highly malignant or there is evidence of metastasis.
Is there anything else I should know?
It is e to recognize that ear canal tumors may grow without much outward evidence, only causing subtle signs in your pet. Regularly rechecking with your veterinarian may assist with early detection if your pet suffers from recurrent or chronic ear infections or shows signs of pain or discomfort.
