Post on 23-Feb-2016
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Winkie LynchAcc 140663Trisha Oura, DVM10/25/2010
11 yo MC Shih Tzu Presents for evaluation of large soft palate
mass 6 mos progressive respiratory stridor and
increased effort, decreasing activity, recent onset dysphagia
Palate mass seen on exam by rDVM
Winkie Lynch
Sedated oral exam: large mass deviating the soft palate ventrally, obstructing view of the epiglottis
FNA of mass: kertainized squamous debris◦ Inconclusive interpretation due to low cellularity
CT:
Winkie Lynch
Primary Differential:Cholesteatoma
Severe otitis media Usually not expansile
Neoplasia◦ Middle/inner ear
Usually soft tissue swelling w/ contrast enhancement Usually permeative lysis of tympanic bulla/petrous
temporal bone◦ External ear
Soft tissue mass within ear canal (enhancement)
DDX
Epidermoid cyst within the middle ear
Keratin debris surrounded by keratinized stratified squamous epithelium
VRUS paper describes 3 components (cyst, matrix, perimatrix) but not really used
What is a Cholesteatoma?
Congenital◦ Start with a normal, intact tympanic membrane◦ No otitis media◦ Inclusion or rest of squamous epithelium forms a cyst◦ Can be recognized late in life
Acquired1. Metaplastic transformation of normal epithelium2. Retraction of tympanic membrane into middle ear3. Migration of epithelium from perforated membrane into middle ear4. Basement membrane breach w/ migration of cells from membrane into subepithelial space
Most cases in dogs occur w/ otitis media (therefore = acquired)
How are Cholesteatomas Formed?
Slow or rapid expansion of cyst◦ Keratin or sebaceous material accumulates
Mild-severe inflammatory response◦ Cytokine production varies◦ Can become infected
How are Cholesteatomas Formed?
Cholesterol granuloma reported in few dogs◦ Benign expansive lesions that develop in middle
ear and other normally aerated bony cavities◦ Occurs w/ hemorrhage, obstruction of ventilation◦ Cholesterol precipitates (from RBC membrane or
mucosa) to form crystals granulomatous reaction
24% of people w/ cholesteatoma have cholesterol granulomas◦ Also occur w/ chronic otitis media, tumors
Role of Cholesterol?
Incidence > 11% of dogs with otitis media
Several case series:◦ M > F, mean age ~ 7 yo◦ Many with history of chronic otitis
Clinical signs (similar between reports): ◦ Head tilt◦ Peripheral vestibular◦ Ataxia◦ Pain on opening mouth◦ Increased respiratory noise/respiratory effort (rare)
Signalment/Signs
CT features of middle ear cholesteatoma in dogs. VRUS. 2010. 51(4):374-379◦ Unilateral expansile mass w/o contrast
enhancement** Keratin debris = avascular = no enhancement
◦ Severe bone changes (slow progressive growth) Lysis, proliferation, sclerosis
◦ Minimal air remains in the tympanic bulla◦ Rarely, periosteal reaction associated with adjacent
TMJ
**prev. reports with heterogeneous enhancement
CT Findings
CT Findings
Trigeminal canal enlargement Pre-contrast cholesteatoma Post-contrast cholesteatoma
Imaging FindingsCT MRI
Cholesteatoma Non-contrast enhancingExpansileHyper-attenuating to brain
T2 hyperintenseLow/intermediate T1 signal
Cholesterol granuloma
Non-contrast enhancingNon-expansileIso-attenuating to brain
T2 hyperintenseT1 hyperintense
** if cholesteatoma and cholesterol granuloma coexist, appearance can be heterogeneous and difficult to interpret
Surgical removal◦ Removal all keratin debris and epithelium
Recurrence◦ Risk factors: inability to open mouth, neurologic signs, bone
lysis, P.aeruginosa◦ Recurrence in humans ~ 5-50%
If no TECA-BO, need chronic treatment with open external ear canal to allow removal of debris
Winkie had TECA-LBO & VBO◦ Cultured S.pseudointermedius, E. faecalis
Treatment/Prognosis
Hardie EM, KE Linder, AP Pease. Aural cholesteatoma in twenty dogs. Vet Surg 2008;37:763-770.
Little CJ, et al. Inflammatory middle ear disease of the dog: clinial and pathological features of cholesteatoma, a complication of otitis media. Vet Rec 1991;128:319-322.
Travetti O, et al. Computed tomography features of middle ear cholesteatoma in dogs. Vet Radiol US 2010;51:374-379.
References