Inflammatory polyp in the middle ear of a dog: a case report

Nasopharyngeal polyps are non-neoplastic masses, originating from the mucosa of the nasopharynx, the tympanic bulla or the Eustachian tube. Inflammatory polyps extending into the tympanic bulla cavity are a common cause of otitis media in cats. In dogs, however, occurrence of middle ear polyps has rarely been reported. The present report describes the findings of the clinical examination, diagnostic imaging and histopathological appraisal of a ten year old male dog with an inflammatory middle ear polyp arising from the mucosa of the Eustachian tube. Clinically, the dog displayed a peripheral vestibular syndrome. Magnetic resonance imaging revealed a hyperintense soft tissue mass filling the right middle ear cavity. Following ventral bulla osteotomy, a polypoid growth with a stalk arising from the auditory tube was surgically excised from the tympanic bulla. Histologically, the polyp was composed of a fibrous connective tissue stroma with discreet infiltration of inflammatory cells and an overlying surface layer of partially ulcerated respiratory epithelium. Similarities and differences between the histological appearance of the present case and the few previously reported records of canine middle ear polyps are discussed, along with a comparative review of etiological, pathogenetic and therapeutic aspects of middle ear polyps in cats and dogs