Clinical analysis and nonsurgical management of 11 dogs with aural cholesteatoma

Abstract

Background Aural cholesteatomas, also called tympanokeratomas, are destructive and expansile growths of keratinizing epithelium that develop in the middle ear. They have been reported sporadically in dogs, and surgery is usually the recommended treatment. Objectives To describe the common clinical, radiological and histological findings of cholesteatoma; to report on the outcome of conservative management. Animals Eleven dogs (13 ears) with cholesteatomas. Methods and materials Medical records were reviewed for dogs diagnosed with cholesteatoma between 2012 and 2018. All dogs had computed tomography (CT) and/or magnetic resonance imaging (MRI) followed by trans‐canal endoscopic procedure (TEP) for removal and biopsy of middle ear lesions. Dogs were then treated with in‐clinic flushing initially weekly tapered to monthly, as well as at‐home ear cleaning and application of topical otic steroid medication, initially daily then tapered to once or twice weekly. Results Nine dogs had a history of chronic otitis externa; head tilt or facial paralysis was present in seven and four cases, respectively. Otic examination identified a protruding nodule in seven ears. CT demonstrated soft tissue‐like material in 12 bullae and expansion in seven bullae. MRI revealed minimally contrast‐enhancing bulla contents in 12 ears. Post‐TEP and with maintenance medical treatment, nine ears had no further signs of middle ear disease during a mean follow‐up of 27.9 months. Conclusions and clinical importance The results suggest that otitis externa may not necessarily precede cholesteatoma in all dogs. MRI appears to be more sensitive than CT for identifying cholesteatomas. Conservative treatment of cholesteatomas could be useful before or as an alternative to surgery.

MRI of a middle ear cholesteatoma in a cat

“…5 The MRI characteristics of the mass in the current study varied from those described in dogs and humans. 4,9,10 In the present case the cholesteatoma was T1 iso to hyperintense, similar to dogs, but unlike humans in which cholesteatomas are typically T1W hypointense. Variations in T1 hypointensity may reflect variations in cholesterol and keratin content.…”

“…The cholesteatoma had a mixed T2W hypo to hyperintensity unlike humans and dogs, in which cholesteatomas are typically T2W hyperintense. 4,9,10 The mass also demonstrated heterogeneous contrast-enhancement, while human and canine cholesteatomas are typically noncontrast-enhancing. 4,9,10 The contrast-enhancement described here may be due to small caliber blood vessels found between cystic spaces, unlike typical cholesteatomas which have been described histopathologically as a single expansive cystic mass.…”

“…4,9,10 The mass also demonstrated heterogeneous contrast-enhancement, while human and canine cholesteatomas are typically noncontrast-enhancing. 4,9,10 The contrast-enhancement described here may be due to small caliber blood vessels found between cystic spaces, unlike typical cholesteatomas which have been described histopathologically as a single expansive cystic mass. 11,12 The T2* characteristics of cholesteatoma in dogs and humans have not been described.…”

“…2,3 Chronic inflammation is thought to play a role in development. [2][3][4] Gradual expansion causes compression and erosion of the middle ear, and secondary infection may lead to acute worsening of clinical signs. 3,5 In the single case report describing feline acquired cholesteatoma, the patient had undergone a ventral bulla osteotomy thirteen years prior for a nasopharyngeal polyp.…”

“…14 Expansion of the tympanic bulla is a common finding in dogs with middle ear cholesteatoma. 4,[6][7][8][9]13,15 The shedding of keratin involved in cholesteatoma growth is thought to result in progressive expansion of the mass and subsequent destruction of adjacent tissue and bone. 3 While the affected bulla in the current case was expanded, this could not be attributed solely to expansion of the mass that occupied only a portion of the tympanic bulla.…”