Cholesteatoma: Diagnosis and Treatment

Cholesteatoma (CSO) is a disease of the middle ear recognised in man and dogs. CSO is very uncommon in man (1 case per 10,000 annually) and is rare in the dog and there are few reports in the literature although its true incidence is not clear and it is possible that some cases are not recognised; one source reported findings seven cases in 62 dogs with confirmed otitis media. A range of breeds affected by CSO have been reported; most patients are beyond the age of 5 years and there is male predisposition.

CSO is caused by the development of an epidermoid cyst within the tympanic cavity which is surrounded by layers of keratinising epithelium; the cyst produces keratin and is also locally destructive causing erosion of the surrounding bone. Despite its destructive growth, CSO is a non-neoplastic condition and is thought to develop as the result of keratin migrating into the tympanic cavity. It has been reported as a complication of lateral bulla osteotomy in brachycephalic dogs.

Symptoms include otorrhea, pain around the ear, pain associated with the temporomandibular joint; neurological signs including facial paralysis and vestibular signs are occasionally seen. Clinical examination may elicit pain on opening of the mouth, detect ipsilateral atrophy of the temporomandibular muscles and identify associated neurological deficits.

Otoscopic examination will often reveal absence of the tympanic membrane and stenosis of the external auditory meatus in some cases; endoscopy of the tympanic cavity itself may reveal accumulations of proliferative debris. Sectioning diagnostic imaging will normally demonstrate filling of the tympanic chamber with debris and variably, stenosis of the external meatus, bony proliferation, expansion of the tympanic cavity and destruction of the surrounding petrosal component of the temporal bone. Microbiological isolation may recover a range or organisms including Pseudomonas, Staphylococcus spp.  [...]