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External auditory canal cholesteatoma: a rare complication of tympanoplasty.

Abstract

The author describes a rare case of external auditory canal cholesteatoma. This particular case occurred in a 20-year- old woman who had undergone a tympanoplasty 1 year earlier. Previous tympanoplasty is one of several known predisposing factors for external auditory canal cholesteatoma. The mass was excised, and it was diagnosed on histopathology. The patient recovered uneventfully.

Introduction

Schofield introduced the term external auditory canal cholesteatoma in 1893 in describing a cholesteatoma that had been caused by an insect. (1) Until 1980, external auditory canal cholesteatoma and keratosis obturans were considered to be different presentations of the same disease. (2) It was then that Piepergerdes et al further characterized the distinctions between the two. (3) They defined keratosis obturans as an accumulation of keratin plugs within the ear canal, and external auditory canal cholesteatoma as bone erosion resulting from squamous tissue at a specific site in the external auditory canal.

Cholesteatoma of the external auditory canal is very uncommon, as it is seen in only 0.1 to 0.5% of patients who present with an otologic disorder. (2,4,5) Affected patients typically present with otorrhea and a chronic, dull pain secondary to the local invasion of squamous tissue into the bony external auditory canal. (3) Hearing loss is not common unless the cholesteatoma invades the middle ear or attic. Only rarely does enough cholesteatoma debris form in the ear canal to cause conductive hearing loss. (6)

In this article, the author describes a new case of external auditory canal cholesteatoma that occurred following a tympanoplasty.

Case report

A 20-year-old woman presented with a history of several symptoms in her right ear. She had a 6-month history of decreased hearing, a 1-month history of an irregular dull otalgia, and a 4-year history of an intermittent discharge that had been partially responsive to medical therapy. One year earlier, she had undergone tympanoplasty in the right ear to improve her hearing. The hearing did improve for 6 months, but then it gradually deteriorated again.

Examination revealed that the right ear canal was completely obliterated at the bony cartilaginous junction and covered with skin. No mastoid tenderness was present. A postauricular surgical scar was visible on the right. The left ear was normal, as were the nose and throat. The Rinne test was negative on the right, the Weber test lateralized to the right, and the results of absolute bone-conduction testing were normal. Audiometry demonstrated a 30-dB conductive hearing loss on the right.A clinical diagnosis of acquired atresia of the external auditory canal was made.

The patient was operated on under local anesthesia, and the ear canal was exposed through a postauricular incision made next to the previous incision. The fibrous tissue that had obliterated the canal at the bony cartilaginous junction was removed. A pearly-white mass was then seen between the stenotic part of the ear canal and the tympanic membrane, and it too was removed. A 3 x 4-mm erosion was noted in the posterosuperior canal wall 5 mm lateral to the annulus. The erosion was only superficial, and the necrotic bone was drilled away. The tympanic membrane was normal. A canaloplasty was performed, and the raw area was grafted with temporalis fascia.

[FIGURE OMITTED]

Histopathologic examination of the resected pearlywhite specimen revealed squamous epithelium covered with multiple layers of keratin and an infiltrate of chronic inflammation (figure). The mass was reported as a cholesteatoma.

The patient's postoperative period was uneventful. At the 6-month follow-up, her external auditory canal was normal, and audiometryshowed closure of the air-bone gap. She remained normal at the 1-year follow-up.

Discussion

The exact etiology of external auditory canal cholesteatoma is unclear. (7) The basic pathogenesis involves canal occlusion. (4) Most cases occur spontaneously or after surgery (tympanoplasty, middle ear surgery, or mastoid surgery) and/or trauma in the auditory canal; preexisting ear canal stenosis or obstruction has also been described as a causative factor. (7,8) Most cases occur in association with chronic otitis externa and/or chronic otitis media. Brookes and Graham opined that when there is obstruction of the canal, desquamation of the epithelium continues and the collection of impacted squamous debris may ultimately modify the canal lining and lead to cholesteatoma formation. (9)

Several classification systems based on the pathophysiologic mechanism and presumed etiology have been reported. In 1990, Farrior (10) described four types of external auditory canal cholesteatoma:

* that which complicates congenital aural atresia and stenosis of the external auditory canal;

* that which follows tympanoplasty, middle ear surgery, or trauma to the skin of the external auditory canal;

* that which is related to keratosis obturans; and

* that which is associated with focal osteitis.

In 1992, Holt (8) speculated on the causes of external auditory canal cholesteatoma and listed five groups of patients in whom this entity may be seen:

* postoperative patients;

* post-trauma patients;

* patients with ear canal stenosis (often congenital);

* patients with ear canal obstruction secondary to tumor or osteoma; and

* a large group of patients in whom the cause is not known.

The reported complications of an external auditory canal cholesteatoma include facial palsy, ossicle erosion, and labyrinthine fistula. (10) These complications can occur as a result of an extensive cholesteatoma extending to the mastoid or the middle ear. (4) Extensive invasion into the mastoid cavity has a propensity to involve the vertical segment of the facial nerve. (2,6,11)

The diagnosis is based on the history, clinical examination, and audiometric findings. Although external auditory canal cholesteatoma has characteristic imaging features (its defining feature on computed tomography is a soft-tissue attenuating mass in the canal with erosion of the adjacent bone), imaging is usually not performed for diagnosis. (7)

Our patient had a predisposing factor for the development of external auditory canal cholesteatoma: postoperative atresia of the canal. The atresia resulted in obstruction of the canal and interfered with the normal migration of the epithelium in that area. This migration was further inhibited by inflammation. The cholesteatoma formed between the tympanic membrane and the stenotic part of the canal.

Those external auditory canal cholesteatomas that occur as a complication of surgery or trauma are more likely than other forms to violate the middle ear cavity, and they commonly require surgical treatment. (11) The choice of procedure is determined by the extent of the cholesteatoma and the surgeon's judgment. Canaloplasty is sufficient for small lesions that do not involve the mastoid air cell. Skin grafting is beneficial when there is a large defect. For patients with a small posterior wall defect that does not involve the middle ear cavity, canal-wall-up mastoidectomy and canal wall reconstruction can be used. For patients who have a large posterior wall defect and involvement of the middle ear cavity, canal-wall-down mastoidectomyis recommended) Cholesteatoma excision must be accomPanied by canaloplasty when a bony or cartilaginous canal stenosis is believed to be the cause of the cholesteatoma. (11)

References

(1.) Schofield RE. Cholesteatoma of auditory canal caused by a bug. Lancet 1893;2:929.

(2.) Zanini FD, Ameno ES, Magaldi SO, Lamar RA. Cholesteatoma of the external auditory canal: A case report. Braz I Otorhinolaryngol 2005;71(1):91-3.

(3.) Piepergerdes MC, Kramer BM, Behnke EE. Keratosis obturans and external auditory canal cholesteatoma. Laryngoscope 1980;90(3): 383-91.

(4.) Lee DH, Jun BC, Park CS, Cho KJ. A case of osteoma with cholesteatoma in the external auditory canal. Auris Nasus Larynx 2005;32(3):281-4.

(5.) Orita Y, Nishizaki K, Fukushima K, et al. Osteoma with cholesteatoma in the external auditory canal. Int J Pediatr Otorhinolaryngol 1998;43(3):289-93.

(6.) Cheng YF, Shiao AS, Lien CF. Pediatric external canal cholesteatoma with extensive invasion into the mastoid cavity. Int J Pediatr Otorhinolaryngol2005;69(4):561-6.

(7.) Heilbrun ME, Salzman KL, Glastonbury CM, et al. External auditory canal cholesteatoma: Clinical and imaging spectrum. AINR Am J Neuroradiol2003;24(4):751-6.

(8.) Holt JJ. Ear canal cholesteatoma. Laryngoscope 1992;102(6): 608-13.

(9.) Brookes GB, Graham MD. Post-traumatic cholesteatoma of the external auditory canal. Laryngoscope 1984;94 ( 5 Pt 1 ) :667- 70.

(10.) Farrior J. Cholesteatoma of the external ear. Am J Otol 1990;11 (12):113-16.

(11.) Martin DW, Selesnick SH, Parisier SC. External auditory canal cholesteatoma with erosion into the mastoid. Otolaryngol Head Neck Surg 1999;121(3):298-300.

Borlingegowda Viswanatha, MS, DLO

From the Department of ENT, Victoria Hospital and Bangalore Medical College and Research Institute, Bangalore, Karnataka, India.

Correspondence: Borlingegowda Viswanatha, MS, DLO, No. 716, 10th Cross, 5th Main, MC'Layout, Vijayangar, Bangalore, 560 040, Karnataka, India. E-mail: drbviswanatha@yahoo.co.in
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Title Annotation:ORIGINAL ARTICLE
Author:Viswanatha, Borlingegowda
Publication:Ear, Nose and Throat Journal
Article Type:Case study
Geographic Code:9INDI
Date:Nov 1, 2009
Words:1417
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