Cholesteatoma

From Dog
White scales filling the middle ear cavity[1]
Gross appearance of middle ear cholesteatoma during surgery. Spongy aspect of the keratinous material; the material spontaneously protruded after enlargement of the bulla opening

Cholesteatoma, a destructive and expanding growth, in the middle ear and/or mastoid process, is a relatively rare cause of otitis media in dogs.

Cholesteatoma are epidermoid cysts lined by a pluristratified keratinizing epithelium containing keratin debris and is characterized by independent and progressive growth, causing destruction of adjacent tissue, especially bone[2].

Cholesteatoma are formed when the tympanum is pushed into the bulla by usually dry concretions. Epithelial debris continues to accumulate within this 'pouch' until it fills the entire bulla. With time, pressure may be placed on the bulla wall to result in thinning of the bone and an actual expansion of the bulla. This condition has been reported in dogs following total ear canal ablation and lateral bulla osteotomy[3].

There is a history of chronic recurrent otitis externa which becomes unresponsive to topical or systemic therapy. There appears to be no breed predisposition, but males appear more predisposed[4].

Clinically affected dogs usually present with otorrhea, otodinia and pain on temporomandibular joint palpation. Other signs such as tilting of the head to the affected side, circling, ataxia and seizures are relatively rare[5].

Otoscopic examination reveals tympanic membrane rupture associated with hyperplastic tissue at the entrance of the middle ear. Pearly growths or white/yellowish scales in the middle ear cavity are often visualized[6].

Diagnosis may be assisted with CT or MRI imaging studies, which shows the presence of an expansive and invasive unvascularized lesion involving the tympanic cavity and the bulla, with little or no contrast enhancement after administration of contrast media. This is almost pathognomonic for this condition[7]. Moreover, Temporomandibular sclerosis is usually concurrently present.

Definitive diagnosis requires histological analysis of biopsied material[8].

Surgery is the only therapy, aimed at removing all keratin debris and stratified squamous epithelium, and to control infection[9]. Recurrence is common[10].

Performing a ventral bulla osteotomy may be preferable when the ear canal appears normal or mildly changed, whilst total ear canal ablation should be performed when the owner is not dedicated to ongoing management of otitis externa or end-stage otitis is present[11].

References

  1. Greci V et al (2011) Middle ear cholesteatoma in 11 dogs. Can Vet J 52(6):631-636
  2. Ferlito A et al (1997) Clinicopathological consultation. Ear cholesteatoma versus cholesterol granuloma. Ann Otol Rhinol Laryngol 106:79–85
  3. Schuenemann RM & Oechtering G (2012) Cholesteatoma after lateral bulla osteotomy in two brachycephalic dogs. J Am Anim Hosp Assoc 48(4):261-268
  4. Davidson EB et al (1997) Removal of a cholesteatoma in a dog, using a caudal auricular approach. J Am Vet Med Assoc 211:1549–1553
  5. Little CJ et al (1991) Inflammatory middle ear disease of the dog: The clinical and pathological features of cholesteatoma, a complication of otitis media. Vet Rec 128:319–322
  6. Hardie EM et al (2008) Aural cholesteatoma in twenty dogs. Vet Surg 37:763–770
  7. Venker-Van Haagen AJ (2005) The ear. In: Schlütersche, editor. Ear, Nose, Throat and Tracheobronchial Diseases in Dogs and Cats. 1st ed. Hannover: Schlütersche Verlagsgesellschaft mbH & Co. pp:1–50
  8. Harran NX et al (2012) MRI findings of a middle ear cholesteatoma in a dog. J Am Anim Hosp Assoc 48(5):339-343
  9. Mason LK et al (1988) Total ear canal ablation combined with lateral bulla osteotomy for end-stage otitis in dogs. Results in thirty dogs. Vet Surg 17:263–268
  10. Hardie EM et al (2008) Aural cholesteatoma in twenty dogs. Vet Surg 37:763–770
  11. Beckman SL et al (1990) Total ear canal ablation combining bulla osteotomy and curettage in dogs with chronic otitis externa and media. J Am Vet Med Assoc 196:84–90