Kaja Troha1, Saba Battelino2
Primary Cholesteatoma of the external
auditory Canal with adjacent structure
invasion: a report of three Cases and
literature review
Primarni holesteatom zunanjega sluhovoda s širjenjem v sosednje
strukture: trije klinični primeri in pregled literature
aBstraCt
KEY WORDS: cholesteatoma, external auditory canal, tissue invasion, imaging, otoscopy, mastoidectomy,
comorbidities
External auditory canal cholesteatoma is a rare condition. In persons with no significant
history of trauma, surgery or pre-existing ear canal stenosis of the affected ear, it is ter-
med primary/idiopathic/spontaneous. While the majority of outer ear canal cholestea-
tomas are limited to the external ear canal itself, the masses have the potential to spread
and destroy adjacent tissues. The aim of our study is to present clinical findings in three
patients with primary external auditory canal cholesteatoma spreading to the surroun-
ding structures. This clinical entity is often misdiagnosed, which leads to a delay in ade-
quate treatment and possible complications. External auditory canal cholesteatoma should
be considered as a differential diagnosis  by otorhinolaryngologists in any case of otitis
externa maligna, otomycosis non-responsive to medication, keratosis obturans, neoplasm
of the outer ear canal etc. In patients with prolonged non-specific symptoms (such as
otorrhea and otalgia), thorough otoscopic examination and appropriate imaging are cru-
cial for a timely diagnosis. Tissue biopsy is necessary, especially in advanced stages of
the disease, to exclude malignancies and to plan surgical treatment accordingly. The dis-
crepancy between symptom severity and local extent of the disease in our patients stres-
ses the importance of early recognition and regular follow-up, especially in persons with
associated risk factors (advanced age and comorbidities).
1 Kaja Troha, dr. med., Klinika za otorinolaringologijo in cervikofacialno kirurgijo, Univerzitetni klinični center Ljubljana,
Zaloška cesta 2, 1000 Ljubljana; kaja.troha@gmail.com
2 Izr.prof. dr. Saba Battelino, dr. med., Klinika za otorinolaringologijo in cervikofacialno kirurgijo, Univerzitetni klinični
center Ljubljana, Zaloška cesta 2, 1000 Ljubljana
427Med Razgl. 2022; 61 Suppl 2: 427–441
ORL 2022_Mr10_2.qxd  2.9.2022  13:00  Page 427
less common than middle ear cholesteato-
ma (5, 6). It is classified as primary or
idiopathic or spontaneous when no signi-
ficant history of trauma, surgery, radiation
or other causes of priorly present ear canal
stenosis of the affected ear are found. The
pathogenesis of the disease is poorly under-
stood. Potential risk factors for its deve-
lopment have been proposed, including
microangiopathy (nicotine abuse, diabetes),
microtrauma, remnants of the first branc-
hial cleft, and age-related changes in epit-
helial migration (9, 10). The symptoms are
non-specific, otorrhea and otalgia being the
most common ones (7). The majority of
EACCs are limited to the outer ear canal.
Still, the disease has the ability to spread
and destroy adjacent structures – the tem-
poromandibular joint (TMJ), hypotympa-
num, mastoid cavity, facial nerve, skull
base etc. (8). Several staging systems of
EACCs are available (11). The diagnosis lar-
428 Kaja Troha, Saba Battelino Primary Cholesteatoma of the external auditory Canal with adjacent …
iZvleČek
KLJUČNE BESEDE: holesteatom, zunanji sluhovod, destrukcija tkiv, slikovna diagnostika, otoskopija,
mastoidektomija, komorbidnosti 
Holesteatom zunanjega sluhovoda je redka klinična najdba. Pri bolnikih brez poškodbe,
operacije, obsevanja ali iz drugih vzrokov znane prisotne zožitve sluhovoda na prizade-
tem ušesu gre za primarni/idiopatski/spontani holesteatom zunanjega sluhovoda. Kljub
temu da je večina holesteatomov te vrste omejena na sam zunanji sluhovod, imajo lezije
potencial k širjenju in uničenju priležnih tkiv. V prispevku smo želeli predstaviti klinične
značilnosti in obravnavo treh bolnikov s primarnim holesteatomom zunanjega sluhovoda,
ki se širi v sosednje strukture. Ta klinična entiteta je pogosto napačno diagnosticirana, kar
vodi v zamudo z ustreznim zdravljenjem in poveča možnosti za področne ali sistemske zaple-
te. Otorinolaringologi naj na primarni holesteatom zunanjega sluhovoda posumijo pri vsa-
kem primeru malignega vnetja zunanjega sluhovoda, Otomikoze, neodzivne na zdravljenje,
primerih keratosis obturans-a in neoplazmah zunanjega sluhovoda. Pri bolnikih z vztra-
jajočimi nespecifičnimi simptomi (bolečina in izcedek iz ušesa) sta natančen otoskopski
pregled in slikovna diagnostika ključna za optimalno obravnavo. Pred načrtovanjem ope-
rativnega posega je predvsem pri razširjenih oblikah bolezni za izključitev malignih tvorb
pomembna biopsija tkiva. Nesorazmerje med stopnjo težav in razširjenostjo holesteato-
mov pri preučevanih bolnikih poudarja pomen zgodnjega prepoznavanja in rednih kon-
trolnih pregledov, še posebej pri osebah z večjim tveganjem (starost, pridružene bolezni).
introDUCtion
External auditory canal (EAC) cholestea-
toma is a non-neoplastic formation in the
outer ear canal. It is histologically consi-
dered an epidermoid cyst. It causes osteo-
necrosis and sequester formation in the
bony EAC with its invasion of the kerati-
nizing squamous epithelium. The first
researcher to describe this entity was
Toynbee in 1850, using the term »speci-
mens of molluscum contagiosum« in the
EAC. In 1893, Scholefield described it more
accurately as »epithelial debris in the ear
canal«. It was defined and distinguished
from keratosis obturans, which is the most
similar differential, by Piepergerdes in
1980. Researchers Naiberg et al. were the
first to describe the disease histopatholo-
gically in 1984 (1–4). External auditory
canal cholesteatoma (EACC) is a rare con-
dition with an incidence rate of around
0.30/100.000 per year, making it 60 times
ORL 2022_Mr10_2.qxd  2.9.2022  13:00  Page 428
gely relies on recognition upon clinical exa-
mination by the otorhinolaryngologist and
on appropriate imaging. Tissue biopsy is
essential in advanced lesions before defi-
nitive surgical treatment to exclude mali-
gnancies. Apart from keratosis obturans, the
most common diseases mimicking EACC
are otitis externa maligna and squamous
cell carcinoma (8, 9). Treatment is not stan-
dardised, as it depends on the extent of the
disease and most commonly includes ear
canal curettage (11).
Our study aims to describe the symp-
toms, clinical findings, and disease mana-
gement in three patients with primary
EACC spreading to adjacent structures. 
MetHoDs
Medical documentation of three patients
(Patient A, B and C) was reviewed. 
Medical Cases
All our patients were males over 65 years
of age. Patient A presented with progres-
sive otorrhea and ear canal pruritus, per-
sisting for two months. Patient B and C
experienced hearing loss and otalgia for
three and four weeks, respectively. Patient
B also reported aural fullness. All com-
plaints were unilateral, two on the right side
and one on the left. All three patients had
a positive medical history for comorbidi-
ties – arterial hypertension (all patients),
diabetes and transitory ischemic attack
with neck artery stent placement (patient
B), and smoking habit (patient A). Otoscopy
and CT scans performed in all patients
revealed characteristic lesions in EAC, rai-
sing suspicion of cholesteatoma. In patient
A, the masses were occupying the inferior
anterior portion of the EAC, spreading to the
TMJ area and posterior canal wall. In
Patient B, the mass invaded the mastoid
cavity and the hypo- and mesotympanum.
Cholesteatoma in patient C was expan-
ding from the posterior canal wall into the
mastoid cavity. All patients underwent sur-
gical treatment under general anaesthesia.
Modified canal wall down (CWD) mastoi-
dectomy was performed in patient A. In
patients B and C, ear canal curettage was
performed to remove cholesteatoma tissue
and serve as tissue biopsy, as it was impos-
sible to differentiate between cholesteato-
ma and possible malignancies with the CT
scan alone. With malignancies excluded,
patient C, due to mastoid invasion, under-
went a CWD mastoidectomy in a separate
procedure. All cholesteatomas were remo-
ved in total. Histopathological examination
confirmed the diagnosis of cholesteatoma
in all patients. Pre- and postoperative audio-
metric testing revealed only minor addi-
tional conductive hearing loss in patients
with mastoidectomy after surgery, with
Patient C already having a known combi-
ned hearing loss before surgery. In patient
B, a residuum of the disease was found six
months after initial treatment, requiring re-
curettage of the EAC, which was success-
fully performed. The patients are monitored
during regular follow-ups, which periodi-
cally include imaging (high resolution com-
puter tomography (HRCT) or MRI), and
haven’t shown any signs of disease so far
(all more than 4 years after surgery). 
Detailed clinical presentation and mana-
gement are described below. 
Patient a 
A 71-year-old male patient presented to the
tertiary ENT centre with progressive wor-
sening of otorrhea and external ear canal
pruritus on the right ear persisting for
two months. The symptoms were not
responding to treatment with oral anti-
biotics, and thorough local cleansing had
been performed every second day in the
secondary outpatient clinic. The patient’s
past medical history was significant for
tobacco use and allergic rhinitis. There
was no history of trauma, stenosis or pre-
vious surgery performed on the affected ear.
Otoscopic examination revealed a chole-
429Med Razgl. 2022; 61 Suppl 2:
ORL 2022_Mr10_2.qxd  2.9.2022  13:00  Page 429
steatoma-like mass occupying the inferior
anterior portion of the right external audi-
tory canal spreading to the temporomandi-
bular joint area and into the posterior canal
wall. A fibrose pocket was present laterally
to the cholesteatoma. Medially, an intact
tympanic membrane was seen. The CT scan
demonstrated a cholesteatoma of the outer
ear canal with possible growth into the
middle ear cavity (figure 1). Microbiological
swab testing of the ear discharge was nega-
tive for pathogens. Preoperative pure tone
audiometry revealed bilateral sensorineu-
ral hearing loss in high frequencies without
conductive hearing loss. A modified CWD
mastoidectomy was performed in general
anaesthesia. The posterior upper ear canal
was drilled, and the ear canal dilated. The
tympanum was left intact, without entry
through the atticus, to affect the patient’s
hearing as little as possible. The TMJ area
was affected just up to the capsule, with no
430 Kaja Troha, Saba Battelino Primary Cholesteatoma of the external auditory Canal with adjacent …
direct invasion to the joint. The cholestea-
toma mass was removed in total (figure 2).
The ear canal was packed with gel foam soa-
ked with antibiotics. A temporalis fascia
graft was used to cover the exposed bone
before repositioning the meatal skin in
the area and below the lifted tympano-mea-
tal flap. Pure tone audiometry postopera-
tively revealed only minor additional
conductive hearing loss (figure 3). An intra-
venous antibiotic was administered posto-
peratively on the ward. During regular
follow-ups, the denuded bone in front of the
TMJ and in the inferior part of the EAC was
carefully monitored for appropriate healing.
After 15 months, a platelet-rich plasma
treatment was administered to aid re-epit-
helisation, which was visibly improving
on every examination. No signs of disease
recurrence were evident during follow-
ups, four years after initial treatment for the
time of this article. 
a) b)
Figure 1. Preoperative CT scan in patient A, both sections showing soft tissue mass in the right EAC with
middle ear invasion. A) axial view, B) coronal view.
Figure 2. Postoperative CT scan in patient A, coronal view, post-canal wall down mastoidectomy showing
no cholesteatoma on the right ear.
ORL 2022_Mr10_2.qxd  2.9.2022  13:00  Page 430
Patient B
A 67-year-old man presented to the tertia-
ry centre due to persistent otalgia and
hearing loss on the left ear starting three
weeks before referral. His comorbidities
were diabetes mellitus on metformin and
hypertension. His past medical history was
significant for a transitory ischemic attack
20 years prior, along with the placement of
a stent in the right neck artery. No evidence
of trauma or previous surgery on the affec-
ted ear was reported. An expanded left
external ear canal was evident upon otos-
copic examination. In the inferior canal,
wall granulations and sequesters of dead
bone were seen. The diagnosis of EACC was
suggested. Audiometric testing revealed
a symmetrical sensory-neural loss bilate-
rally. Microbiological swab samples were
obtained prior to intravenous antibiotic
administration (Ciprofloxacin) on the ward.
They were positive for Turicella otidis, sen-
sitive to the selected antibiotic. The CT scan
demonstrated demineralization and a defect
of the bony area of left ear canal, filled with
accumulated bone spurs and dense tissue
(figure 4). The mass undermined the lower
part of the tympanic membrane, and local-
ly invaded the tympanic cavity into the
hypo- and mesotympanic area, cranially up
to the epitympanum and minimally inva-
ded the latter as well. The auditory ossic-
les were not destructed, only mildly
demineralized due to associated inflam-
mation. The mastoid cells contained a thick
collection without significant changes of
the mastoid cell walls. External ear canal
curettage and biopsy were performed in
general anaesthesia. Histopathological exa-
mination confirmed the diagnosis of cho-
lesteatoma – fragments of necrotic bone
tissue and keratin scales. Postoperatively,
an MRI was performed, showing no rem-
nants of the cholesteatoma. After six weeks
of parenteral antibiotics and meticulous
cleansing of the EAC, the patient was disc-
harged. The inflammation was in regres-
sion, and an intact tympanic membrane was
seen with no signs of epithelium growth.
Appropriate healing of the ear canal was
431Med Razgl. 2022; 61 Suppl 2:
Figure 3. Postoperative pure tone audiometry testing in patient A, two months after surgery (image of
preoperative testing is not available, based on written documentation, the test revealed sensorineural hea-
ring loss up to 55 dB at 4000 Hz on the right ear, and sensorineural hearing loss up to 60 dB at 4000 Hz,
30 dB at 6000 Hz and 65 dB at 8000 Hz on the left ear, with no conductive hearing loss bilaterally).
ORL 2022_Mr10_2.qxd  2.9.2022  13:00  Page 431
evident. Antibiotic treatment for another
four weeks after discharge was prescribed.
The patient had regular check-ups posto-
peratively. A control MRI after two months
revealed no cholesteatoma masses. Contrast
build-up superficially in the medial EAC
and the inferior part of tympanic membrane
was observed, possibly due to inflammation
or postoperatively. Careful observation was
indicated. Another MRI was later obtained
in four months, which showed new unspe-
cific thickening in the lower and anterior
portion of the ear canal. Accumulation of
epithelium debris towards the anterior
canal wall was seen otoscopically. The
patient was admitted for re-curettage in
general anaesthesia. The cholesteatoma
recurrence was removed in total along with
the cholesteatoma sac. The tympanic mem-
brane was unchanged, as well as the midd-
le ear. No remnants of cholesteatoma or
epithelium debris were seen postoperatively.
432 Kaja Troha, Saba Battelino Primary Cholesteatoma of the external auditory Canal with adjacent …
a) b)
Figure 4. Preoperative CT scans in patient B, axial view, showing: A) bone erosion of the left external
auditory canal; B) a soft tissue mass in the left external auditory canal.
Figure 5. Postoperative MRI in patient B, T2-weighted sequence, axial view, upon follow-up (five years after
treatment) without a cholesteatoma mass in the left external auditory canal.
a) b)
Figure 6. A) preoperative pure tone audiometry testing; B) postoperative pure tone audiometry testing in
patient B.
ORL 2022_Mr10_2.qxd  2.9.2022  13:00  Page 432
A postoperative MRI showed diminished
contrast build-up in the area where it
was previously described. During follow-
ups, appropriate reepithelization of the
exposed bone was seen. The patient repor-
ted unchanged hearing postoperatively. No
changes in hearing were observed during
audiometric testing (figure 6). Regular
cleansing was necessary postoperatively
with regular follow-up MRI, which showed
no cholesteatoma recurrence up to this
point, over five years after surgical treat-
ment. 
Patient C 
81-year-old male presented with otalgia
and hearing loss of the right ear gradually
worsening in the past month. He had
a known bilateral symmetric combined hea-
ring loss for 15 years and was wearing
a hearing aid on the left ear. His comorbi-
dities were arterial hypertension, clinical
depression and prostate enlargement. No
history of trauma, surgery or prolonged
infection of the affected ear was reported.
Otoscopy revealed an obstructed right outer
ear canal in two-thirds with white epithelial
masses, which were removed by aspiration.
Dry and hardened cerumen was seen behind
the masses with only partially removable
granulated epithelium. Suspicion of possi-
ble bone sequestra and outer ear canal cho-
lesteatoma was raised. In the microbiological
swab, Escherichia coli was isolated and trea-
ted accordingly. A CT scan demonstrated
osteomyelitis of the temporal bone. Bone
fragments and cholesteatoma masses were
seen in the right EAC with the destruction
of the posterior ear canal wall and a defec-
tive bone barrier between the EAC and the
mastoid (figure 7). The tympanic membra-
ne was intact. An ear canal curettage and
biopsy were performed under general ana-
esthesia. Using the endaural approach, the
EAC was dilated, and bone fragments with
the cholesteatoma sac were removed. The sac
was present inferiorly to the tympanic mem-
brane. No invasion of the middle ear was evi-
dent, however, the invasion in the mastoid
could not be assessed. The posterior canal
wall and the area below the tympanic mem-
brane were drilled. The removed tissue
was sent for pathological examination,
confirming the cholesteatoma diagnosis.
Osteomyelitic bone fragments were micro-
biologically inspected, demonstrating seve-
ral pathogens. Targeted antibiotic treatment
was administered in the ward. Due to the
poor visibility of the mastoid and the suspec-
ted invasion of the cells, a CWD mastoi-
dectomy was performed in another surgery
under general anaesthesia with lat. n. facia-
lis monitoring. Retroauricularly. The mastoid
was trepanned, demonstrating dense liquid
in the mastoid cells. The cholesteatoma sac
along with thick mucosa were removed
433Med Razgl. 2022; 61 Suppl 2:
Figure 7. Preoperative CT scans in patient C, axial view, showing a soft tissue mass in the right EAC with
destruction of the posterior ear canal wall.
ORL 2022_Mr10_2.qxd  2.9.2022  13:00  Page 433
entirely. Less than expected post-CWD con-
ductive hearing loss in high frequencies was
documented with audiometric testing posto-
peratively (figure 8). After six weeks of
intravenous antibiotic application, the
patient was discharged and regularly exa-
mined during follow-ups at the outpatient
clinic. Successful epithelisation of the radi-
cal cavity was observed. No cholesteato-
ma recurrence was seen upon regular
examinations four years after cholestea-
toma removal.
DisCUssion
incidence and Demographics 
EACC is a term describing a cystic lesion
lined by keratinizing stratified squamous
epithelium in the external auditory canal.
It is a rare finding, accounting for 1/1000
otological patients (12). The annual inci-
dence rate of EACC in the general popula-
tion is between 0.19 and 0.3 per 100,000
inhabitants in Switzerland, and Denmark
and Greenland (5, 15). In comparison, the
annual incidence of middle ear cholestea-
toma is around 9.2/100,000 individuals (8).
In a study in 2018, Herz et al. described
a significantly higher incidence in Europe
than previously reported: 0.97 per year
per 100,000 inhabitants. The researchers
assumed that previous studies only inclu-
ded patients treated in tertiary centres,
without mild cases treated by general prac-
titioners and without possible asympto-
matic cases (14). In another recent Chinese
study by He et al. in 2021, an even higher
incidence was reported, 23.2 per one mil-
lion residents. Underestimating the inci-
dence in previous studies was similarly
attributed to only taking into account inter-
mediate, advanced, or surgically treated
lesions. The study could not exclude regio-
nal or ethnic specificity of the incidence
(11). EACC has been described in all age
groups, but more commonly occurs in
older patients with comorbidities. No una-
nimous gender predilection of the disease
has been concluded, however, in our study
the patients were all males (5, 6, 13, 14).
Pathogenetics and Predisposing
Factors
Embryologically, the EAC is formed from
the pharyngeal groove between the first and
434 Kaja Troha, Saba Battelino Primary Cholesteatoma of the external auditory Canal with adjacent …
Figure 8. Postoperative pure tone audiometry testing in patient C, four months after surgery – priorly known
bilateral combined sensory loss (preoperative testing picture is not available, based on written documentation).
ORL 2022_Mr10_2.qxd  2.9.2022  13:00  Page 434
second branchial arches, i. e. ectoderm, lined
by the squamous epithelium. Epithelial skin
from the tympanic membrane (TM) migra-
tes towards the ear canal and carries kera-
tin debris for removal. The basic mechanical
characteristic of the EACC is found to be the
narrowing or obstruction in the outer ear
canal that blocks this epithelium migration.
The obstruction contributes to cholestea-
toma formation by creating an entrapment
or isolation pockets of keratin debris (8, 9).
Bunting et al. proposed that the close con-
tact between the skin and the bone of the
canal leads to epithelial abnormality with
increased keratotic activity, which can
result in cholesteatoma (20). According to
the study by Brookes and Graham, the
obstruction of the EAC causes cholestea-
toma through its involvement in epithelial
desquamation, which leads to a collection
of squamous epithelial debris (21).
This close contact or obstruction may
occur in the ear canal caused by surgery,
trauma, radiation, stenosis following osteo-
ma, exostosis, congenitally, inflammation
or years of bisphosphonate treatment. In
those cases, it is termed secondary EACC
(14). In 1992, Holt divided EACCs in five
categories based on different aetiologies −
congenital, posttraumatic, iatrogenic, spon-
taneous, post-obstructive or post-inflam-
matory (10). The simple division into
primary/idiopathic/spontaneous EACC and
secondary EACC has later been well esta-
blished and most commonly used. Primary
EACC therefore develops in the absence of
known prior processes occurring in the
affected ear. According to recent studies, it
may be more common than secondary
EACC (5, 22). None of our patients had any
known identifiable aetiological factors and
were therefore considered primary EACCs. 
The etiopathogenetic events of primary
EACC are unclear, as well as the predispo-
sing factors for its development. It has been
priorly suggested that underlying local
periosteitis causes the stenosis in primary
EACC through the mechanisms of a reacti-
ve process (12). More recently, the hypothesis
of abnormal epithelium migration and pro-
liferation in individuals developing prima-
ry EACC has been proposed by Makino and
Amatsu. Their study has shown that the
migratory rate of the epithelium in the infe-
rior wall of the external ear canal is slower
in patients with primary EACC than in those
without EACC (18). This theory is debatable,
since it has recently been challenged by
a study, which showed no difference in the
rate of epithelial migration between normal
ears and those affected by EACC (32). This
reduction or loss of normal epithelial migra-
tion, however, does occur in the aging pro-
cess, which is probably the reason for higher
EACC occurrence rates in the elderly (19).
Other predisposing factors have been sugge-
sted, such as the disruption of local micro-
circulation due to repeated microtrauma from
the use of cotton swabs, smoking, diabetes
mellitus, hearing aids etc. The dehiscence of
the petrotympanic fissure, the persistence of
first branchial cleft epithelium and other
branchial arch anomalies also result in the
retention of epithelial masses and are pos-
sible risk factors for EACC (13−17, 23).
Recent immunohistochemical studies
have given researchers additional insight
into EACC development. Increased levels of
various growth factors in patients with
EACC have been reported, such as an ele-
vated vascular endothelial growth factor
and hepatocyte growth factor. These indi-
cate tissue hypoxia and increased apopto-
sis of epithelial cells and debris formation,
respectively, and are a step further in under-
standing this clinical entity (24, 25).
In our study, the patients were all over
65 years old and had a positive medical
history for comorbidities, one of the patients
was wearing a hearing aid. These anamne-
stic facts are consistent with the literature
describing the EACC risk factors and could
contribute to disease development in our
patients. 
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ORL 2022_Mr10_2.qxd  2.9.2022  13:00  Page 435
location in the ear canal and
extension to the surrounding
tissues
The most common location of idiopathic
EACC is known to be the posterior inferior
canal wall. Relatively poor blood supply to
the skin along the inferior aspect of the
canal, the effect of gravity and chewing
movements have all been found to promote
the invasion of cholesteatoma in this part
of the EAC (11, 13).
While most EACCs remain limited to
the external canal, the disease can spread
to surrounding structures. Cholesteatoma
extension is often larger than suggested by
clinical examination (26). It can invade the
structures anteriorly to the TMJ, inferior-
ly to the hypotympanum, posteriorly to the
mastoid, where it can cause damage to the
facial canal, semicircular canals, or sigmoid
sinus. The mass can spread superiorly to the
facial nerve or to the base of the skull. The
tympanum and the TM are usually not
affected, except in advanced lesions of
middle ear invasion, when it is difficult to
differentiate it from middle ear cholestea-
toma. However, the TM may be inflamed
and sometimes perforated. In less extended
lesions of the middle ear, the distinction
between middle and external ear chole-
steatoma can be made based on the loca-
tion of the main body of the lesion and the
direction of TM destruction (inside out). (8,
22, 27). According to He et al., EACCs have
five direction of expansion pathways:
lesions can spread downward or forward
within the temporal bone adjacent to the
inferior or anterior wall of the EAC and are
found to be less destructive. The other two
invasion pathways are backward or upward.
These invade into the mastoid air cells or
through the lateral attic wall upward into
the epitympanum. They can invade the
temporal bone air cells and can spread
rapidly. The last pathway is the inward inva-
sion, which means lesions extend medial-
ly to the TM, resulting in invagination,
ischemia, or perforation. These can invade
through the TM into the tympanic cavity (11). 
Owen et. al reported that the most
common adjacent structure involvement of
the EACC is the fibrous capsule of the TMJ,
followed by the mastoid and the middle ear
(5). In a study by Heilbrun et al., disease
extension was found in all their 13 subjects;
in five cases, into the middle ear, in four
cases, as erosion of mastoid air cells, and
in two cases, erosion of the facial nerve
canal. Consistently with similar studies,
they reported it was rare for lesions them-
selves to break inward through the TM into
the tympanic cavity. Shadows on CT scans
around the ossicular chain were common
according to their study, which they attri-
buted to infections rather than EACC invol-
vement. They concluded that the TM
appeared to be a resilient natural barrier to
cholesteatoma invasion. As the disease
seems to easily destroy bone structures, TM
tissues are more difficultly impacted by
cholesteatoma destructive mechanisms
(14, 17, 22).
The invasion of the EAC can result in
complications, such as facial palsy, ossi-
cular erosion, or labyrinthine fistula. A case
of EACC presenting as a cerebellar abscess
has been reported, despite the extremely
rare occurrence of intracranial complica-
tions (8, 28).
Consistent with the recent literature, in
all our cases the inferior portion of the EAC
was involved, which is the most common-
ly described location. In the first patient, the
mass was occupying the anterior inferior
portion of the right EAC spreading to the
TMJ area and into the posterior canal wall.
The cholesteatoma and dead bone tissue in
the second patient undermined the lower
part of the TM and locally invaded the tym-
panic cavity into the hypo- and mesotym-
panic areas, cranially up to the epitympanum
and minimally invaded the latter. In the last
patient, cholesteatoma with osteomyelitis
and destruction of the posterior ear canal
436 Kaja Troha, Saba Battelino Primary Cholesteatoma of the external auditory Canal with adjacent …
ORL 2022_Mr10_2.qxd  2.9.2022  13:00  Page 436
wall was described. The mass was spreading
from the posterior canal wall into the
mastoid cavity. The mild and unspecific cli-
nical signs and symptoms may explain
the reason our patients presented in the ter-
tiary centre relatively late after the disea-
se onset (three weeks minimum), when the
cholesteatoma had already invaded the
neighbouring structures. 
Clinical Presentation
EACC usually presents with non-specific
symptoms. The most common symptoms
reported in the literature are otalgia and
otorrhea. Otalgia has not been consistent-
ly described, ranging from cases of vague,
mild discomfort to chronic dull pain and
severe pain (9, 10, 12). Owen et al. propose
that otalgia is a symptom already related
to advanced cases of cholesteatoma with the
invasion of surrounding structures, as it
was significantly present only in patients
with EACC invading the TMJ and the
mastoid. Otorrhea is another symptom
they found inconsistently described and
were unable to relate it to the extension of
the EACC or coexisting symptoms. Subjective
symptoms such as »fullness« or »occlusion
feeling«, which diminishes after ear clean-
sing, were found to be more consistently
reported by patients. Researchers in the
study also found a relatively large share of
patients presenting as asymptomatic: 24%
of all patients. This is consistent with the
previously reported rate in literature, bet-
ween 25 and 31% (5). Hearing loss is tra-
ditionally not a common symptom in EACC,
unless described as a blockage of the ear
canal or in cases of middle ear invasion (5,
6). In a study by Vrabec and Chaljub, they
reported cases of 12 patients with sponta-
neous EACC and no hearing loss until late
in the course of the disease (29). Conversely,
in a study by He et al., the most common
symptom they found was hearing loss, or
sense of blockage, in 78.7%, followed by
acute or chronic otalgia in 73.4% and otorr-
hea in 28.2%, others being tinnitus, pruri-
tus; in one case, they also found facial
paralysis. They proposed the patients most-
ly seek treatment with acute symptoms,
such as otalgia or otorrhea, whereas hearing
loss described as blockage is also present in
this disease before, tracing retrospectively
(11). It can be proposed that these additio-
nal unspecific symptoms are often not
reported as the main complaints as they
develop more gradually and are, therefore,
noted to a lesser extent. 
In this paper, we only report advanced
cases of EACC. Our findings are consistent
with the existing literature, which descri-
be additional symptoms in advanced
lesions, apart from the most common ones.
Two of our cases reported hearing loss and
otalgia, while the other presented with
otorrhea and ear canal pruritus. All the
symptoms persisted for minimally 3 weeks
and were unspecific for this disease. The
patients’ complaints were subjectively not
as severe as one would have expected in an
advanced stage of the disease. These facts
stress the importance of early suspicion of
EACC in patients with prolonged unspeci-
fic symptoms. 
importance of imaging 
To obtain more information about a mass
presenting in the EAC following thorough
clinical examination and suspicion of EACC
raised in otoscopy, appropriate imaging is
essential. Often the extent of the disease is
clinically underestimated. To delineate any
soft tissue in the temporal bone, HRCT is
the imaging modality of choice when
suspecting cholesteatoma. A CT scan aids
to confirm the diagnosis to assess the
extension of the disease and to plan the
treatment. In 50% of cases, it usually shows
eroded contact surface between the chole-
steatoma and the ear canal and osteolysis.
A soft tissue mass in the absence of osteo-
lysis, however, is unspecific on HRCT to
exclude other differentials. An MRI with
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ORL 2022_Mr10_2.qxd  2.9.2022  13:00  Page 437
diffusion weighted imaging (DWI) should
be conducted in that case. An MRI without
DWI is non-specific as granulation tissue
(otitis maligna externa) and shows similar
patterns of signal through this imaging
modality (13, 17, 22, 27).
Differential Diagnosis
Especially in the early stages of the disea-
se, EACCs are often misdiagnosed. This is
due to their unspecific clinical appearance
with erosions, inflammation and keratin
accumulation, while yielding non-specific
complaints from patients. Physicians need
to differentiate EACC from conditions such
as malignant otitis externa, keratosis obtu-
rans, post-inflammatory medial canal fibro-
sis, Langerhans’ acromegalic disorder,
malignant tumours and otomycosis non-
responsive to medication (9). A soft tissue
plug in the EAC is seen in keratosis obtu-
rans and in post-inflammatory medial canal
fibrosis. The latter is usually differentiated
by patient history of recent EAC inflam-
mation (8).
Keratosis obturans (KO) is a disease,
where the accumulation of desquamated
keratin in the external canal without bone
erosion occurs. KO is more commonly
observed in younger individuals and pre-
sents bilaterally with acute severe pain with
conductive hearing loss. Otorrhea is rare-
ly reported. On imaging, smooth enlarge-
ment of the ear canal is observed without
bone destruction or sequestrum forma-
tion. The TM is usually affected by the pat-
hological process, contrary to EACC, where
it is mostly normal. The differentiation
between the two entities is clinically impor-
tant because the management of KO is
usually conservative (4, 5, 8, 27).
Malignancies must also be ruled out in
cases of EACC. On imaging, malignant
otitis externa and squamous cell carcino-
ma (SCC) of the EAC both show osteolysis
and can appear as EACC. Clinical features
usually distinguish these entities from one
another. Malignant otitis externa is an infec-
tion of the EAC that typically affects older
diabetic patients. It is a rapidly progressing
disease with observable granulation tissue
with diffuse osteolysis in the EAC presen-
ting with severe otalgia, otorrhea and hea-
ring loss. On the contrary, EACC progresses
in a slower manner. In SCC, the lesions
usually involve the ear canal as part of
tumour dissemination, rather than being
the originating location. Despite this fact,
biopsy is usually the only definite distinc-
tion tool to differentiate the two conditions
(12–14, 17). Another differential is an EAC
osteoma, which is a rare benign tumour. It
usually starts at the tympanomastoid or
tympanosquamous suture near the osteo-
cartilaginous junction as a small bony
mass. Patients remain asymptomatic unless
there is obstruction of the EAC (30).
Langerhans acromegalic disorder is also
a disease with similar manifestations in the
ear canal, especially due to the most com-
mon symptom of otorrhea. It is a condition
that occurs in children; retroauricular edema
in the mastoid is additionally seen with
a typical laboratory finding of an increased
erythrocyte sedimentation rate, which is
usually normal in younger patients with
EACC (17, 30).
In our patients, CT scans demonstrated
an extended disease pattern guiding the cli-
nician to the diagnosis of EACC, but biopsy
was necessary to undoubtedly differentiate
lesions from malignant conditions.
staging and treatment 
Several staging systems are available for
EACC. On the basis of histopathology and
clinical symptoms, Naim (2005) classified
EACC into four stages: Stage I meaning
canal epithelium hyperplasia, stage II mea-
ning periosteitis, Stage III meaning canal
erosion, and Stage IV meaning erosion of
the adjacent structure (31). The Shin (2010)
staging system, based on both clinical and
imaging findings, is more convenient for
438 Kaja Troha, Saba Battelino Primary Cholesteatoma of the external auditory Canal with adjacent …
ORL 2022_Mr10_2.qxd  2.9.2022  13:00  Page 438
clinical application. It differentiates bet-
ween four stages. Stage I indicates that the
EACC lesion is limited to the external audi-
tory canal, stage II means that the EACC
lesion invades the tympanic membrane
and middle ear, in stage III the cholestea-
toma creates a defect of the EAC and invol-
ves the mastoid air cells, and stage IV
indicates that the EACC lesion is in the TMJ
and beyond the temporal bone. This staging
system describes treatment used in their
study for each stage. In stage I, they recom-
mend local care or canaloplasty, stage II
recommends canaloplasty and tympano-
plasty, stage III canaloplasty with mastoi-
dectomy with or without tympanoplasty,
and removal of mass by various approac-
hes is recommended for stage 4 (32).
A newer staging system has been proposed
in 2021 by He at al. as the Shin system for
them fails to illustrate the severity of the
disease in more advanced lesions. Stage I
contains invasion without bony lesions,
stage II invasion within the EAC and pos-
sible bone erosion seen as a rough edge or
localized defect of the bone, Stage III inva-
sion beyond the EAC involving the mastoid
air cells or tympanic cavity but within the
temporal bone, with subtypes A: backward
invasion into the mastoid air cells, B:
inward or upward invasion into the tym-
panic cavity, C: invasion into the tympanic
cavity and mastoid air cells. Stage IV
means invasion beyond the temporal bone
or complications caused by the involvement
of structures adjacent to the temporal bone.
They suggest treatment plans for separa-
te stages as follows: conservative treatment
with ear canal curettage of the EAC for
stage I. For Stage II lesions, which are limi-
ted to the EAC and do not invade the tym-
panic cavity or mastoid cells, curettage with
additional canaloplasty, or EAC wall recon-
struction in larger defects. In lesions that
involve the mastoid (IIIA), a mastoidecto-
my or partial mastoidectomy may be the
treatment of choice. If the lesion invades
the tympanic cavity (IIIB), tympanoplasty
may be necessary in large TM perforations.
For Stage IV lesions, the surgical approach
and technique depend on the extent of the
invasion (11).
All of our patients underwent surgical
treatment under general anaesthesia. In
patient A, a canal wall down (CWD) modi-
fied mastoidectomy was performed due to
disease extension. Ear canal curettage was
performed in patients B and C to confirm
the diagnosis prior to extensive surgical
treatment in patient C and as a removal tool
in patient B. In a separate further procedure,
Patient C had a modified CWD mastoidec-
tomy performed due to mastoid invasion.
The posterior canal was removed, but the
tympanic cavity was not punctured or alte-
red. All cholesteatomas were removed in
total, and histopathology confirmed the dia-
gnosis of cholesteatoma in all patients. Pre-
and postoperative audiometric testing was
conducted, showing only minor additional
conductive hearing loss in patients with
a CWD mastoidectomy. This can be attri-
buted to the mentioned surgical modifi-
cation, which left the patients without
significant conductive hearing loss. It needs
to be noted that Patient C had severe bila-
teral combined hearing loss prior to sur-
gery. 
The treatment of EACC is, therefore, not
standardized and depends on the extent of
the condition. This needs to be assessed cli-
nically, by biopsy and imaging modalities.
To prevent further disease progression and
restore normal epithelial migration in the
EAC, the lesions as well as necrosed bone
tissue must be fully removed, leaving the
canal wall as smooth as possible. Regular
follow up with debris cleansing is important
to prevent the re-accumulation of keratin. 
There is little known information on the
recurrence rates in patients with EACS. In
one of our patients, a residuum of the disea-
se was found 6 months after initial treat-
ment, requiring re-curettage of the EAC,
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ORL 2022_Mr10_2.qxd  2.9.2022  13:00  Page 439
440 Kaja Troha, Saba Battelino Primary Cholesteatoma of the external auditory Canal with adjacent …
which was successfully performed. After
surgery, a DWI is the most appropriate ima-
ging option to exclude disease recurrence
even in asymptomatic patients with fully
removed lesions (13). Our patients are
monitored during regular follow-ups and
have not shown any signs of disease for at
least 4 years. 
ConClUsion
Despite recent reports of a higher incidence
of EACC cases, EACC remains a rare disea-
se. Most lesions are limited to the ear canal,
but can invade the surrounding tissues.
Clinical examination usually underesti-
mates the disease progression. Apart from
thorough otoscopic examination, appropri-
ate imaging is crucial for a timely and cor-
rect diagnosis. Tissue biopsy is necessary in
surgical planning to exclude malignancies.
In our patients, the discrepancy between
symptom severity and local extent of the
disease was evident. This stresses the
importance of early disease recognition,
especially in persons with associated risk
factors, such as advanced age and other
comorbidities. Recognizing it as a distinct
entity is important as its management is dif-
ferent from that of its differential diagnoses.
Ear, nose, throat physicians should consider
this a differential in any case of otitis
externa maligna, otomycosis non-respon-
sive to medication, keratosis obturans, neo-
plasm of the EAC and in patients with
prolonged non-specific symptoms, such
as otalgia and otorrhea. The case of EACC
reoccurrence in one of our patients demon-
strates the significance of regular follow-
ups with imaging even in fully removed
lesions. 
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