Tympanic cholesteatoma have been renamed by our derm colleague: tympanokeratoma

Clinical aspects of middle ear tympanokeratoma in dogs diagnosed through advanced imaging, otoendoscopy and histopathological evaluation

Cristiane Bazaga Botelho, Rafaella Tortoriello, Sandra Nogueira Koch, Julio Israel Fernandes

Background
Tympanokeratoma, also known as aural cholesteatoma, is a benign epidermoid cyst commonly located in the middle ear. It can expand and erode adjacent structures and is often associated with chronic otitis externa or otitis media. The condition is likely underdiagnosed in veterinary medicine due to its non-specific clinical manifestations and reliance on advanced diagnostics.

Methods
-Study Design: Retrospective analysis of 890 medical records from dogs with otitis media at a veterinary dermatology center in Brazil, focusing on 100 cases with confirmed tympanokeratoma.

-Diagnostics: Data included advanced imaging (CT or MRI), otoendoscopy, and histopathological examination of keratinous material collected from the middle ear.

-Inclusion Criteria: Complete medical records, confirmed diagnosis of tympanokeratoma through histopathology, and material originating from the middle ear.

Results
Demographics:
-Brachycephalic breeds, particularly pugs (51%) and French bulldogs (35%), were most commonly affected.
-Most affected dogs were male (71%) and had a median age of 6.8 years.

Clinical Manifestations:
-Chronic otitis externa was present in 81% of cases, often accompanied by neurological signs such as head tilt (66%), ataxia (31%), and nystagmus (25%).
-Non-neurological symptoms included dysacusis (60%), otalgia (18%), and oral pain during chewing (14%).

Imaging Findings:
-Advanced imaging identified middle ear changes in all cases but was inconclusive for tympanokeratoma in 60% of dogs.
-Features suggesting tympanokeratoma included tympanic bulla expansion (29%) and bulla lysis (11%).

Otoendoscopy and Histopathology:
-Common findings were the absence of the tympanic membrane and the presence of dense, pearly yellowish material in the bulla.
-Histological analysis confirmed tympanokeratoma as a keratinized cyst lined by stratified squamous epithelium.

Limitations
The study relied on retrospective data, which may limit the consistency and detail of findings. The reliance on brachycephalic breeds may limit generalizability to other dog populations.

Conclusions
Tympanokeratoma primarily affects brachycephalic dogs and presents with otitis externa and peripheral vestibular syndrome. Advanced imaging alone may be insufficient for diagnosis; otoendoscopy and histopathology are essential. This study highlights the importance of combining diagnostic approaches to detect and manage tympanokeratoma effectively.

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