Ear canal tumors can arise from skin, earwax and oil glands, bone, connective tissue, muscle, or deeper skin layers. Tumors of the external canal and outer ear are more common than those of the middle or inner ear. Malignant (fast-growing or spreading) ear canal tumors are more common in cats than dogs, although they are less common than other skin tumors.
Long-term ear canal inflammation can lead to abnormal tissue growth and, eventually, tumors. Bacterial infections that increase earwax production might also promote cancerous changes. In cats, ear canal tumors are more often malignant than benign (noncancerous), especially after age 11.
Middle-aged to older cats more commonly develop benign and malignant canal tumors, while young cats (3 months to 5 years) more often have inflammatory polyps (growths).
Signs include ongoing discharge (which can be waxy, pus-filled, or bloody) from one ear, foul odor, head shaking, scratching, swelling, draining abscesses (pockets of pus) below the ear, or deafness. If the middle or inner ear is affected, loss of balance, head tilt, and neurological signs can occur. Persistent one-sided inflammation that doesn't respond to treatment raises concern for a tumor.
Common external ear canal masses in cats include nasopharyngeal (nose and throat) polyps, squamous cell carcinoma, and earwax gland tumors. Other tumors that can occur in the middle or inner ear include lymphoma, fibrosarcoma, and squamous cell carcinoma.
If surgery is required, referral to a board-certified veterinary surgeon is often recommended, especially when the middle ear is involved.
Also see Tumors of the Skin.
Inflammatory Polyps
Nasopharyngeal polyps are small, pink inflammatory growths found in the external ear canals of young cats (usually 3 months to 5 years old). They also occur in the mucous membranes lining the throat and the auditory tube (the channel connecting the upper throat to the middle ear). Polyps may be present at birth or develop from chronic bacterial middle ear infections, often linked to long-term upper respiratory infections.
Symptoms resemble other middle ear problems, like balance or coordination issues and inflammation of the visible part of the ear.
Diagnosis involves otoscopic exam of ear canals with the cat sedated. The vet might need to use gentle suctioning with a tube to remove discharge and see the polyp. CT or MRI might be used if a mass is suspected in the bone behind the ear.
Treatment is surgical removal, plus therapy for any associated infection.
Earwax Gland Tumors
Earwax gland tumors (benign or malignant) occur in middle-aged or older cats. Many tumors obstruct the canal, leading to external or middle ear inflammation and pus-filled or bloody discharge. If the middle ear is involved, balance loss is common. Malignant tumors can spread to nearby lymph nodes and salivary glands, so surgical removal is often recommended.
Benign tumors may be removed surgically by a procedure called partial ear canal ablation. Less invasive laser surgery guided by video-otoscopy can help in many cases unless the bone behind the ear is involved. For malignant tumors, complete opening of the ear canal and surgical division of the middle ear bone are recommended.
Treatment depends on the cat’s age and the tumor’s size and location. Your veterinarian will suggest a plan with the best chance of a positive outcome.
Also see professional content regarding tumors of the ear canal.
