External auditory canal osteoma: a case report

Abstract

p>External auditory canal (EAC) osteomas are rare, solitary benign unilateral lesion. Small lesions are incidentally diagnosed and larger lesions produce symptoms of pain, ear discharge and defective hearing. Diagnosis is made based on a combination of clinical history and examination, radiographic imaging, and histopathology. They are usually confused with exostosis which are multiple, bilateral, smooth-bordered, broad-based lesions without deep extension. We present a case of 21-year-old male patient who came to our outpatient department, with complaints of left ear blocking sensation for past 6 months. On evaluation, it was diagnosed as left EAC osteoma and the same was excised via post-auricular approach. This case is being presented for its rarity</p

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International Journal of Otorhinolaryngology and Head and Neck Surgery | October 2021 | Vol 7 | Issue 10 Page 1704
International Journal of Otorhinolaryngology and Head and Neck Surgery
Sneha S et al. Int J Otorhinolaryngol Head Neck Surg. 2021 Oct;7(10):1704-1707
http://www.ijorl.com
pISSN 2454-5929 | eISSN 2454-5937
Case Report
External auditory canal osteoma: a case report
Sneha S., Sowmya Gajapathy*, Srikanth G., Ramesh V., Jayita Das Poduval
INTRODUCTION
Osteoma in the EAC manifests as a rare benign tumour,
which is solitary, unilateral and slow growing
pedunculated mass in the bony canal.1 It shows a
predilection for the EAC, mastoid cortex, facial bones
and mandible.2 Its incidence is 0.05% of total otologic
surgery.3 Chronic irritation/inflammation to the inner part
of the EAC leads to ingrowth of the bone through suture
lines. Osteoma of ear canal are usually incidental finding
and they are unilateral and solitary. They show clinical
presentations such as hearing loss, otorrhea, otalgia, otitis
externa and cholesteatoma. Diagnosis is made based on a
combination of clinical history and examination,
radiographic imaging, and histopathology. Differential
diagnosis includes exostosis, adenoma, hard cerumen,
foreign body, xanthogranuloma and other benign fibro-
osseous lesions.
CASE REPORT
A 21-year-old male patient came to our out-patient
department with complaints of left aural fullness for 6
months, which was insidious in onset, progressive, with
no aggravating or relieving factors. It was associated with
decreased hearing. History of habitual use of ear buds
present. No history of swimming, trauma, ear discharge
or ear pain. On otoendoscopic examination, a bilobed
mass that was completely obscuring the ear canal was
noted, which was hard in consistency and non-tender
(Figure 1). Tympanic membrane in the left side could not
be visualized, right side was normal.
HRCT of temporal bone showed a pedunculated bony
osteoma arising from the anterior wall of left EAC
measuring 6.5×4×9 mm, with underlying cerumen
(Figure 2 and 3). Pure tone audiometry showed moderate
conductive hearing loss (46 db HL) in the left side.
Patient underwent excision of left EAC osteoma through
a post auricular approach under general anesthesia
(Figure 4). Osteoma was removed through its peduncle
and raw area was covered with skin flap (Figure 5). The
specimen was sent for histopathological evaluation. Post
operative period was uneventful.
ABSTRACT
External auditory canal (EAC) osteomas are rare, solitary benign unilateral lesion. Small lesions are incidentally
diagnosed and larger lesions produce symptoms of pain, ear discharge and defective hearing. Diagnosis is made based
on a combination of clinical history and examination, radiographic imaging, and histopathology. They are usually
confused with exostosis which are multiple, bilateral, smooth-bordered, broad-based lesions without deep extension.
We present a case of 21-year-old male patient who came to our outpatient department, with complaints of left ear
blocking sensation for past 6 months. On evaluation, it was diagnosed as left EAC osteoma and the same was excised
via post-auricular approach. This case is being presented for its rarity.
Keywords: Osteoma, EAC, Exostosis
Department of Otorhinolaryngology, Aarupadai Veedu Medical College and Hospital, Puducherry, India
Received: 14 August 2021
Accepted: 08 September 2021
*Correspondence:
Dr. Sowmya Gajapathy,
E-mail: yasowm@yahoo.com
Copyright: © the author(s), publisher and licensee Medip Academy. This is an open-access article distributed under
the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial
use, distribution, and reproduction in any medium, provided the original work is properly cited.
DOI: https://dx.doi.org/10.18203/issn.2454-5929.ijohns20213910

Sneha S et al. Int J Otorhinolaryngol Head Neck Surg. 2021 Oct;7(10):1704-1707
International Journal of Otorhinolaryngology and Head and Neck Surgery | October 2021 | Vol 7 | Issue 10 Page 1705
Figure 1: Otoendoscopic image of left external
auditory canal bilobed osteoma.
Figure 2: HRCT temporal bone coronal view.
Figure 3: Axial view of pedunculated osteoma arising
from anterior wall of left EAC.
Figure 4: Left EAC osteoma via post auricular
approach.
Figure 5: Excised left ear canal osteoma.
Figure 6: Histopathological slide of the excised
specimen-lamellated bone and bone marrow with few
fibrovascular channels, suggestive of osteoma.

Sneha S et al. Int J Otorhinolaryngol Head Neck Surg. 2021 Oct;7(10):1704-1707
International Journal of Otorhinolaryngology and Head and Neck Surgery | October 2021 | Vol 7 | Issue 10 Page 1706
Histopathological examination reports confirmed the
specimen to have features suggestive of osteoma with
areas of lamellated bone, bone marrow and few
fibrovascular channels (Figure 6).
DISCUSSION
The solitary osteoma is an uncommon unilateral lesion,
attached to the tympansquamous or tympanmastoid
suture line, almost always in the outer half of the ear
canal. It is seen commonly in the second decade of life
and can be seen in a wide range of age groups.3 Osteomas
of temporal bone are rare, and have been reported in the
middle ear, internal auditory canal, squamous temporal
bone, mastoid, internal auditory canal, cerebellopontine
angle and in the EAC.4 Most common suggested eitiology
of osteoma are trauma, chronic infection, and hormonal
dysfunction.5-7 Graham showed that the most common
site of origin of EAC osteomas is from the vascular pre-
osseous connective tissue in the tympan squamous or
tympan mastoid suture lines.1 Kim et al reported osteoma
mostly originated in the tympanic wall, and this is
regardless of the tympano-squamous or tympano-mastoid
suture line.8
The most common clinical entity that shares a very
similar picture with osteoma in terms of presentation is
exostosis. The differentiation between these two are still
a dilemma. Exostosis are multiple, bilateral, appear as
wide based and smooth lesions of the EAC and are
usually considered to be a reactive condition secondary to
multiple cold-water immersions or recurrent otitis
externa.9,10
There are limited histopathological studies done for
osteoma and exostosis as these lesions are drilled during
surgical removal. Exostosis are concentric, dense layers
of subperiosteal bone with abundant osteocytes, lacking
fibrovascular channels covered with periosteum and
squamous epithelium.1 Studies by Fenton et al suggested
that fibrovascular pathway is a characteristic feature of
osteoma, and could also be found in exostosis also and so
it could not be differentiated histopathologically.2 In
some cases they might also occur together.11 Osteoma
and exostosis has been categorized as a single clinical
group, by some researchers, whereas, Schuknechts
classifies the lesions limited to the EAC as exostoses and
lesions that extend beyond the canal as osteoma.12,13
The management of osteoma of EAC depends on the size,
symptoms and site of origin. Regular aural toileting can
be done for small, asymptomatic lesions. Excision of the
osteoma must be actively considered as the treatment of
choice in symptomatic patients with large lesions. The
location of the osteoma in relation to the isthmus of the
EAC is the main deciding factor for surgery. A post-
auricular approach is used for medially placed osteoma
and a trans-canal approach for laterally placed
neoplasm.14 The approaches used are post aural, endaural
and trans-meatal. Though the most preferred route was
post aural due to better exposure and complete removal,
nowadays with the advent of endoscopes and better
equipment, minimally invasive trans-meatal route is now
being preferred for EAC osteoma and exostosis removal.3
The osteoma is usually excised through its pedicle and
the base is drilled to decrease the incidence of
recurrences.5 Grinblat et al performed drill canaloplasty in
245 cases of EAC osteomas and exostosis and reported
no recurrence in their cases.15 Some of complications
encountered during the removal of EAC osteoma are as
follows: EAC posterior wall injury, tempero-mandibular
joint injury, ear drum and ossicular injury, peripheral
paralysis of facial nerve and chorda tympani damage,
sensorineural hearing loss and narrowing of canal lumen.
Piezoelectric device is a new innovation in the field of
osteoma surgery. It is a bony scalpel that uses micro
vibrations at ultrasonic frequency so that soft tissues will
not be damaged even on accidental contact with the
cutting tip. With an experienced otologist the
piezoelectric device is considered suitable for bone
surgery and for removal osteomas of the EAC.16
Literature shows that there is increased risk of
development of EAC cholesteatoma secondary to long-
standing EAC obstruction and chronic inflammation,
further leading to bony canal erosion and complications
such as sigmoid sinus thrombosis and neck abscesses.17-19
CONCLUSION
Thus, any symptomatic EAC osteoma is removed
surgically, the approach is determined by the size,
location and experience of the surgeon. Though by
literature asymptomatic lesions are usually managed
conservatively, based on the multiple cases reported, we
can conclude that EAC osteomas, which were initially
asymptomatic, if neglected could lead to complications
which are life-threatening. Hence once identified these
EAC lesions should be removed electively to give better
prognosis.
Funding: No funding sources
Conflict of interest: None declared
Ethical approval: Not required
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Cite this article as: Sneha S, Gajapathy S, Srikanth
G, Ramesh V, Poduval JD. External auditory canal
osteoma-a case report. Int J Otorhinolaryngol Head
Neck Surg 2021;7:1704-7.