JPC SYSTEMIC PATHOLOGY
Signalment (AFIP Accession #2382810): A cat
HISTORY: Tissue from a cat with a history of dysphagia. Large, fleshy masses were present in the ear and underneath the tongue.
HISTOPATHOLOGIC DESCRIPTION: Oropharyngeal mucosa (per contributor):
Expanding the submucosal connective tissue and elevating the overlying mucosa is a polypoid mass that is composed of mature collagen interspersed with numerous small to medium caliber blood vessels. Multifocally, there are small aggregates of inflammatory cells throughout the lesion composed of variable proportions of neutrophils, lymphocytes and plasma cells, with fewer macrophages. Multifocally, the collagen bundles are separated by clear spaces and lymphatics are moderately dilated (edema) and there is multifocal hemorrhage. The mucosal epithelium is predominantly stratified squamous and forms multiple folds resembling papillary projections, with few areas of ciliated epithelium. There is multifocal erosion and ulceration of the epithelium which is partially covered with eosinophilic debris and fibrin admixed with cellular and karyorrhectic debris (necrosis) as well as viable and degenerate neutrophils (serocellular crust).
MORPHOLOGIC DIAGNOSIS: Oropharyngeal mucosa (per contributor): Polyp, with chronic-active inflammation, erosion and ulceration, breed unspecified, feline.
- Most commonly occurs in cats and dogs, less commonly in horses
- In cats, non-neoplastic inflammatory masses arising within the middle ear or auditory tube
- Most common non-neoplastic mass in cats, primarily seen in young cats 1-3 years of age
- In cats, most arise from the middle ear or auditory canal and undergo expansile growth within the nasopharynx or the external ear canal
- Recurrence is common
- Cats may have nasopharyngeal polyps originating from the middle ear, OR inflammatory polyps originating from the nasal turbinates (also termed feline mesenchymal nasal hamartoma) which is a separate condition
- Proposed causes: chronic upper respiratory tract infection, otitis media, ascending middle ear infections via auditory tubes, congenital defects
- There is controversy as to whether polyps are secondary to inflammation or if the presence of polyps predisposes the patient to inflammation by impairing auditory tubule drainage
- Nasopharyngeal polyps originate from ciliated epithelium of the tympanic cavity/middle ear mucoperiosteum or less commonly from the external ear canal
- Nasal polyps arise from the ethmoturbinates
- Recent argument for designation of inflammatory polyps of the nasal turbinates in cats (specifically IPNT) as feline mesenchymal nasal hamartoma, due to presence of woven bone as part of the proliferating stroma and erythrocyte filled spaces
- A familial predisposition has been seen in Abyssinian and Himalayan kittens
TYPICAL CLINICAL FINDINGS:
- Extension of mass into the pharynx: Dyspnea, dysphagia, stridor, voice change and gagging
- Involvement with nasal cavity: Sneezing, nasal discharge, and protrusion through the nares, and epistaxis has been reported
- Involvement with middle ear = ataxia, Horner’s syndrome, and or facial nerve paralysis
TYPICAL GROSS FINDINGS:
- Moist, glistening and spherical, oval to elongated (often pedunculated) masses
- Within the ear canal, polyps are usually smooth-surfaced red masses
- Frequently protrude out of the pharyngeal orifice of the eustachian tube and can displace the soft palate
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- Feline nasopharyngeal polyps consist of loose fibrovascular core covered with ciliary respiratory or squamous epithelium
- Surface epithelium may undergo squamous metaplasia or be ulcerated
- The detection of ciliated epithelium aids in the histological confirmation of nasopharyngeal polyps but presence of pseudoglands within the core extending to the surface confirms middle ear origin
- Often accompanied by edema and mixed inflammatory cell infiltrates (lymphocytes, plasma cells, macrophages, neutrophils)
- Goblet cells may be present
- May have a chronically inflamed edematous core resembling myxomatous tissue
- Secondary bacterial rhinitis and sinusitis are common
- Older lesions may be more fibrous; may have lymphoid follicles
- Nasal polyps originating from the turbinates in cats may have woven bone / bony metaplasia (but not nasopharyngeal polyps)
For gross findings:
- Fungal granuloma (cats - Cryptococcus neoformans, dogs-Rhinosporidium seeberi)
- Neoplasia (pedunculated fibroma, papilloma, adenocarcinoma)
- Hemorrhagic nasal polyps (progressive ethmoid hematoma) are relatively common in horses and arise from the ethmoid turbinate region of the nasal cavity
- Nasal polyps arise from middle ear or auditory tube in other domestic species and are uncommon but also reported in sheep, horses and dogs
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- Galloway PE, Kyles A, Henderson JP. Nasal polyps in a cat. J Small Anim Pract. 1997;38:78-80.
- Greci V, Mortellaro CM, Olivero D, Cocci A, Hawkins EC. Inflammatory polyps of the nasal turbinates of cats: an argument for designation as feline mesenchymal nasal hamartoma. J Feline Med Surg. 2011;13(4):213-9.
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- Muilenburg RK, Fry TR. Feline nasopharyngeal polyps. Vet Clin North Am Small Anim Pract. 2002;32(4):839-49.
- Njaa BL: The Ear. In: Pathological Basis of Veterinary Disease. ed. Zachary JF, 6th ed. St. Louis, MO.; Mosby-Elsevier: 2017:1252-1253.
- Njaa BL: Special Senses. In: Jubb, Kennedy and Palmers Pathology of Domestic Animals. ed. Maxie MG, 6th ed., vol. 1, Philadelphia, PA: Elsevier-Saunders: 2016:498-499.
- Rosenblatt AJ, Zito SJ, Webster NS. Pathology in practice. What is Your Diagnosis? J Am Vet Med Assoc. 2014;244(1):37-39.
- Wenzel AR, Wack AN, Beck SE, Bronson E. Pathology in practice. Nasal and nasopharyngeal polyps. J Am Vet Med Assoc. 2012;241(7):885-87. Wilson DW. Tumors of the respiratory tract. In: Meuten DJ, ed. Tumors in Domestic Animals. 5th ed. Ames, Iowa: Iowa State Press; 2017:477.