Volume 2, Issue 1 , Pages 34-39, March 2007
A case of osteoma with cholesteatoma of the external auditory canal and cerebellar abscess
Article Outline
Summary
An osteoma of the external auditory canal is an uncommon unilateral lesion that is often asymptomatic. The association of osteoma with cholesteatoma of the external auditory canal and middle ear cleft is very rare. Here a case of osteoma and cholesteatoma of the external auditory canal with invasion into the middle ear cleft and cerebellar abscess is reported for its rarity.
Keywords: Osteoma, Cholesteatoma, External auditory canal
1. Introduction
An osteoma of the external auditory canal is an uncommon benign tumor with an incidence estimated to be 0.05% of total otological surgery [1].
Cholesteatoma of the external auditory canal is uncommon, being observed in 0.1–0.5% of patients who presents with an otological disorders [1], [2], [3].
The association of an osteoma with a cholesteatoma is extremely rare, and has been described in only few reports [1], [2], [4]. Here an unusual case of osteoma with cholesteatoma of the external auditory canal and cerebellar abscess is reported along with review of literature.
2. Case report
A 12 years old female patient presented with history of decreased hearing on the right side for the past 3 years and recurrent right ear discharge for the past 2 years.
Patient had recurrent ear discharge for the past 2 years. It was small in quantity and foul smelling and some times associated with fever and pain. Patient used to get relief with medication. Patient had sense of imbalance and difficulty in walking since 2 months. Fever and headache started 1 month back. It was irregular, associated with pain and discharge in the right ear.
Four years back patient had noticed a small swelling in the right ear canal. It was gradually increasing in size. Initially it was asymptomatic, but after 1 year it was associated with decreased hearing. Patient was advised surgery. But patient did not undergo surgery due to financial problems.
On examination patient was febrile, neck stiffness was present and cerebellar signs were positive. Fundus examination showed bilateral papilloedema and bilateral gaze evoked nystagmus was present. There was no focal motor or sensory deficit.
Examination of the right ear showed swelling in the right ear canal, completely filling the canal. Swelling was hard, nontender and surface was covered with normal skin. It was arising from the posterior and inferior portion of the ear canal. Deeper portion of the canal could not be visualised. There was a scanty foul smelling ear discharge. There was no mastoid tenderness. Left ear, nose and throat were normal.
CT scan showed a bony mass in the lateral part of the right ear canal, with a narrow base, completely obstructing the canal (Fig. 1). A soft tissue density was seen in the external auditory canal and in the middle ear and mastoid. Posterior and inferior walls of the external auditory canal were eroded. There was a hypo dense shadow in the right cerebellar hemisphere with isodense periphery, enhancing on contrast administration (Fig. 2). Ventricles were dialated. CSF pressure was elevated. Audiogram showed mixed hearing loss with air conduction of 60
db and bone conduction of 30db.
Fig. 1.
CT scan showing bony mass in the lateral part of the right ear canal (black arrow) and a soft tissue mass (white arrow).
Fig. 2.
CT scan showing cerebellar abscess on the right side.
Clinically diagnosis of osteoma with cholesteatoma of the external auditory canal and cerebellar abscess was made.
Patient underwent right retromastoid suboccipital craniectomy and cerebellar abscess excision. Abscess was attached to the petrous part of the temporal bone. Postoperative recovery was uneventful. Pus culture was sterile.
After 2 weeks patient was taken up for the management of ear problem. Mastoid was exposed through postaural incision. There was a oval bony swelling in the lateral part of the bony ear canal. It was arising from the posteroinferior wall of the ear canal, base was narrow and ear canal was completely occluded (Fig. 3).
Fig. 3.
Intraoperative photograph showing bony swelling in the lateral part of the bony ear canal (arrow) arising from the posteroinferior wall.
Initially cortical mastoidectomy was done. Posterior and inferior canal wall was eroded and external auditory canal and mastoid were filled with cholesteatoma. The tympanic membrane and ossicles were destroyed. Vertical portion of facial canal was dehiscent. Bony mass and posterior canal wall was removed. Cholesteatoma sac was completely removed from the ear canal, mastoid and middle ear. Radical mastoidectomy with a wide meatoplasty was done. Patient recovered well in 6 weeks. Evaluation of biopsy specimen confirmed the diagnosis of osteoma (Fig. 4) with cholesteatoma of external auditory canal (Fig. 5). Postoperative CT scan did not show any recurrence of the cerebellar abscess (Fig. 6).
Fig. 4.
Photomicrograph of osteoma showing fibro vascular channel (arrow) and mature dense lamellar bone (H&E: 10×).
Fig. 5.
Photomicrograph of cholesteatoma showing stratified squamous epithelium and overlaying lamellar sheets (arrow) of keratin (H&E: 10×).
Fig. 6.
Postoperative CT scan did not show any recurrence of the cerebellar abscess.
3. Discussion
Osteoma of the external auditory canal is a relatively rare, benign tumor that usually cause no symptoms [2]. The etiology of osteoma includes trauma, surgery, radiotherapy chronic infection and glandular factor such as pituitary dysfunction. The precise etiology is still unknown and considered to be the true bony tumor [1], [5].
Although osteoma has been reported in all parts of the temporal bone, external auditory canal is the most common site. Its incidence peaks in the fourth decade of life, and male to female ratio is known to be 2–3:1 [1].
Osteoma of the external auditory canal is usually unilateral, solitary, discrete, pedunculated bony mass arising from the external auditory canal along the tympano mastoid or tympano squamous suture lines, adjacent to the bony cartilaginous junction [6].
An osteoma originates from the preosseous connective tissue in these suture lines because they have thicker subcutaneous layer and a richer blood supply than the other bony canal [1].
Osteoma of the external auditory canal grows slowly and remains stable for many years. Symptoms such as conductive hearing impairment or fullness in the ear can arise, if the osteoma grows and a canal obstruction occurs due to osteoma itself or the ceruminal impaction [1].
The pedunculated bony mass is covered by periosteum and squamous epithelium [6]. Histopathologically osteoma composed of discrete fibro vascular channels surrounded by lamellar bone, which is dense and oriented in different directions. These features are the important histological differences that distinguish osteoma from an exostosis [1].
The main complication of osteoma of the external auditory canal is cholesteatoma, which can exhibit accelerated growth in the presence of inflammation such as otitis externa [2].
In 1854, Toynbee was the first author to describe that cholesteatoma originates from external auditory canal as epidermal sheets. Upto 1980, cholesteatoma external auditory canal and keratosis obturans were considered as different presentation of the same disease [3].
Piepergerdes et al. described cholesteatoma external auditory canal and keratosis obturans as two different pathological processes; keratosis obturans as keratin accumulation in the external auditory canal; and external auditory canal cholesteatoma as bone erosion resulting from squamous tissue on a specific spot of the external auditory canal [7].
Exact etiology is not known [1]. The cholesteatoma of the external auditory canal may arise through several mechanisms. Occlusion or narrowing of the external auditory canal is the basic cause [8].
Brookes and Grahams are of the opinion that when there is obstruction to the canal, desquamation of the epithelium continues, and the collection of impacted squamous debris may ultimately modify the canal lining leading to cholesteatoma formation [9].
Several classifications based on the pathophysiological mechanism and the etiologies have been reported [1].
Farrior [10] classified cholesteatoma of the external auditory canal into four groups:
In 1992, Holt [11] speculated upon the causes of cholesteatoma of the external auditory canal and listed five groups in which this entity may be seen:
The reported complication of cholesteatoma of the external auditory canal includes facial palsy, ossicles erosion and labyrinthine fistula [10]. These complications can result from an extensive cholesteatoma extending to the mastoid or the middle ear [1]. With extensive invasion into the mastoid cavity, it has the propensity to involve the vertical segment of facial nerve [3], [8], [12].
There are only 10 previous reports describing cases of external auditory canal cholesteatoma with extensive invasion into the mastoid cavity (Table 1). Review of literature showed that there were only two reported cases of external ear canal cholesteatoma with osteoma and posterior canal mastoid fistula [1], [2], [3], [7], [8], [11], [12], [13], [14], [15].
Table 1. Previous reports of cases with external auditory canal cholesteatoma with extension into the mastoid cavity
| S. no. | Authors | Year | Age | Sex | Intraoperative findings |
|---|---|---|---|---|---|
| 1 | Piepergerdes et al. [7] | 1980 | 53 | M | Erosion of inferior and posterior canal wall with extension to the mastoid tip. Portion of vertical segment of facial nerve was dehiscent |
| 2 | Anthony and Anthony [13] | 1982 | 55 | M | Posterior and inferior canal wall erosion |
| 68 | F | Posterior and inferior canal wall erosion, facial canal wall dehiscent at the origin of chorda tympani | |||
| 3 | Holt [11] | 1992 | – | – | Posterior canal wall erosion |
| – | – | Inferior canal wall erosion with extension to the mastoid tip | |||
| 4 | Hartley et al. [14] | 1995 | 43 | F | Posterior canal wall erosion with cholesteatoma completely surrounding the intact facial nerve and extending medially as far as jugular foramen |
| 5 | Garin et al. [15] | 1997 | 68 | F | Posterior canal wall erosion and inferior wall erosion into the hypotympanum that reached the jugular foramen |
| 6 | Orita et al. [2] | 1998 | 13 | F | Posterior canal wall erosion associated with serous otitis media and osteoma of the ear canal |
| 7 | Martin et al. [12] | 1999 | 43 | F | Posterior canal wall erosion |
| 70 | F | Posterior canal wall erosion, sigmoid sinus and posterior fossa dura was dehiscent, middle ear was involved by cholesteatoma | |||
| 51 | F | Posterior canal wall erosion, vertical portion of the facial canal was dehiscent near the stylomastoid foramen | |||
| 8 | Cheng et al. [8] | 2005 | 9 | F | Inferior canal wall erosion |
| 9 | F | Posterior canal wall erosion, facial canal eroded | |||
| 9 | Lee et al. [1] | 2005 | 49 | M | Posterior canal wall erosion, middle ear cavity involved and osteoma present in the ear canal |
| 10 | Zanini et al. [3] | 2005 | 59 | F | Posterior canal wall erosion with extension into the mastoid, lateral sinus and dura exposed |
| 11 | B. Viswanatha (present study) | 2006 | 12 | F | Posterior canal wall erosion, extension into the middle ear and mastoid with cerebellar abscess. Vertical segment of facial canal was dehiscent. Osteoma present in the ear canal |
External auditory canal cholesteatoma is a rare entity with characteristic imaging features. A soft tissue attenuating mass in the external auditory canal with erosion of the adjacent bone defines the CT presentation of an external auditory canal cholesteatoma. CT is important to evaluate for disease extension into the middle ear cavity and for the integrity of the facial nerve canal, tegmen tympani, and mastoid air cells, because these features may change the surgical management of external auditory canal cholesteatoma [16].
Otogenic brain abscess and meningitis are the common intracranial complication of otitis media with cholesteatoma. Otogenic brain abscess related to otitis media is always located adjacent to the temporal bone, almost exclusively at the temporal lobe and cerebellum. This characteristic location is also indicative of the main mechanism of infection that progresses through the osseous limits of the temporal bone by means of osteitis and erosion of bone [17].
In the present case cholesteatoma had involved middle ear and mastoid and there was associated cerebellar abscess. Cerebellar abscess was adjacent to the temporal bone.
In the present case patient had mixed hearing loss. Mixed or sensory neural hearing loss may result from the longstanding infectious process of the middle ear cavity. Sensory neural hearing loss may be the result of long standing passage of toxic substance through the round window membrane, which is often found in the chronically infected ears with and without cholesteatoma [1].
The main treatment for external auditory canal osteoma is surgical excision. The size and location of osteoma as well as severity of symptoms determine the treatment. Surgical excision is recommended if a growing osteoma results in ear canal obstruction and cholesteatoma [1], [2].
Surgical treatment for external auditory canal cholesteatoma is indicated in the following situations: chronic pain (despite treatment), frequent infection (there is a risk for bacterial resistance), facial palsy or chronic dizziness, progression during followup, involvement of hypotympanum, jugular or mastoid (showed in CT scan), diabetes mellitus or immunosupression (predisposition to otitis externa) [3]. Surgery depends on the extent of destruction [1], [3]. Mastoid extension is one of the indications for surgery [12].
For external auditory canal cholesteatoma with large posterior wall defect and involvement of middle ear cavity, canal wall down mastoidectomy is recommended. Canal wall up mastoidectomy is used selectively when middle ear cavity is not involved. For cases with small posterior wall defect not involving the middle ear cavity, the canal wall up mastoidectomy and canal wall reconstruction can be used [1], [2], [7], [8].
In cases of otogenic intracranial complications, after the installation of clinical therapy and stabilization of neurological conditions, surgical treatment should be considered for ear problems. Evacuation of primary infectious focus is of paramount importance to achieve a good outcome [17].
Our patient had predisposing factor to develop external auditory canal cholesteatoma. Patient had osteoma occluding the external ear canal completely and cholesteatoma of the external auditory canal with invasion into the middle ear cavity and mastoid. Patient also had cerebellar abscess which was treated first. Later through postaural approach osteoma and cholesteatoma was removed and radical mastoidectomy with wide meatoplasty was done.
4. Conclusion
Osteoma with cholesteatoma of the external auditory canal and posterior canal wall mastoid fistula and cerebellar abscess is an extremely rare occurrence. External auditory canal cholesteatoma with extension into the mastoid cavity has the propensity to involve the vertical segment of the facial nerve. Extreme care should be taken to perform any procedure in this area. Good outcomes can be achieved with thorough preoperative evaluation and adequate surgical procedure.
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PII: S1871-4048(06)00105-5
doi:10.1016/j.pedex.2006.12.001
© 2007 Elsevier Ireland Ltd. All rights reserved.
Volume 2, Issue 1 , Pages 34-39, March 2007
