Polyps are benign masses of tissue that can form in many places throughout the body. In this case, the descriptor “nasopharyngeal” is a bit confusing because these masses generally do not originate in the nasopharynx (the area within the throat that lies behind the nasal cavities and above the soft palate*) but from the tubes connecting the middle ear to the nasopharynx (Eustachian or auditory tubes) or from within the tympanic bulla, a part of the middle ear. That said, when they grow large enough, nasopharyngeal polyps can extend into the nasopharynx or even into the external ear canal.
Though technically benign (not having the tendency to spread or worsen appreciably*), nasopharyngeal polyps can cause big problems for cats. They are usually diagnosed in animals under the age of two and cause symptoms that include some combination of the following:
a change in voice
difficulty breathing or eating
discharge from the ear
unsteadiness when walking
changes in the shape of the pupils or movement of the eyes
Of course, these clinical signs are seen with other conditions that affect young cats (e.g., upper respiratory infections and ear infections/mites), but when these more common problems have been ruled-out, the presence of a nasopharyngeal polyp must be considered.
Many nasopharyngeal polyps can be diagnosed by sedating the cat and pulling the soft palate forward within the mouth using an instrument called a spay hook. There really shouldn’t be anything in the space above the soft palate, so when a lump of tissue appears, you have your diagnosis. If the polyp has invaded the middle ear, it may be visible through the tympanic membrane (ear drum) when examining the ears with an otoscope. X-rays or a CT-scan are sometimes necessary to reach a definitive diagnosis.
In the best case scenario, a nasopharyngeal polyp can essentially just be pulled off the tissue from which it is growing, either via the mouth or through the ear if the tympanic membrane is ruptured. The veterinarian applies steady traction on the polyp until it releases, hopefully at its base. Post-op treatment with pain relievers, antibiotics, and corticosteroids is necessary.
Polyps can recur after traction removal and medical treatment. This is more likely if the mass had to be removed via the ear rather than through the mouth. If the polyp does come back, a more invasive surgery called a ventral bulla osteotomy is usually necessary. I’ve never done one of these procedures myself because there are a lot of important veins and nerves that run through the surgical site, and I’m a pretty wimpy surgeon. I’ve referred these patients out to board-certified veterinary surgeons and they’ve all done really well after the procedure.
So, if your cat is ever diagnosed with a nasopharyngeal polyp, take heart in knowing that with appropriate treatment, he or she should go on to live a long and hopefully uneventful (medically-speaking, at least) life.
Dr. Jennifer Coates writing for PetMD