Chapter 16 Inflammatory Polyps
Signalment and History
Nasopharyngeal or inflammatory polyps originate from the eustachian tube or from the middle ear mucosa. Most of these polyps have their origin in the middle ear; however, when they originate in the eustachian tube, growth is usually directed toward the throat. Nasopharyngeal polyps can be found exiting the eustachian tube on the lateral wall of the oropharynx, beneath the soft palate. Retraction of the soft palate with a spay hook reveals their presence. The cat with an oropharyngeal location of its polyp shows respiratory symptoms such as stertorous respiration, voice changes, wheezing, dyspnea, and dysphagia.1
After cleaning the cat’s ear, otoscopic examination reveals a pink to red, fleshy, mobile mass deep in the ear canal (Figures 16-3 and 16-4). When the mass is visible in the external ear canal, it has already protruded through the eardrum, having ruptured it as the polyp grew outward from the tympanic bulla. When this happens, a secondary otitis media can develop as bacteria gain access to the middle ear mucosa.
Manipulating the polyp mass often causes the release of material from the bulla into the external ear canal because the polyp acts as a seal for these middle ear exudates. Polyps can become quite large and may reach the diameter of the ear canal, effectively forming a plug that seals in the secretions in the bulla under it.
Microbiology
Many kittens and grown cats have unrecognized middle ear disease often as a sequela to upper respiratory disease. Otitis media is a consistent feature when nasopharyngeal polyps are found in the ear canal. Many bacterial pathogens have been cultured from the middle ear after bulla osteotomy including Pasteurella, streptococci, staphylococci, and occasionally Bacteroides and Pseudomonas.2 Some bacteria isolated from the middle ear in cats with polyps originate from the upper respiratory mucosa, and some pathogens originate from the external ear canal epithelium. Routine aerobic cultures for respiratory pathogens rarely include Mycoplasma, Bordetella, or Chlamydia, which may be involved in respiratory disease and middle ear disease of cats.3 It was once thought that viruses played a role in development of polyps. In one study, tissues from inflammatory polyps were assayed for feline calicivirus and feline herpesvirus–1 by polymerase chain reaction (PCR). Failure to detect either of these viruses suggests that the persistence of these viruses is not associated with the development of inflammatory polyps.4 In another study, polyps were induced in rats by placing type 3 pneumococci into one middle ear cavity of each rat. In 44% of the rats a polyp developed in the experimentally infected ear. None of the rats developed a polyp in the untreated ear.

Figure 16-5 Multilobulated polyp in a cat. This type of polyp is usually more vascular than solitary-lobed polyps.
Depending on their growth pattern, polyps can grow through the auditory tube toward the nasopharnx or they may grow through the tympanic membrane. When found in the external ear canal, the enlarging polyp mass has grown through the tympanic membrane, creating a permanent opening from the external ear canal to the middle ear. The middle ears of these cats have copious mucus and pus.
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