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M. İ. Şahin et al.
Cholesteatoma
19
MehmetTan, SuatTurgut, andErcolodi Martino
19.1 Introduction
A cholesteatoma is a lesion in which keratinized squamous epithelium accumulates in
the mastoid, middle ear, or petrous bone, causing gradual expansion of these structures and destruction of locoregional tissues [1, 2]. It can affect anatomical and functional structures in the ear. In addition to causing hearing and balance problems, it can
cause irreversible facial paralysis by destroying the facial nerve, which is anatomically located in the ear. In short, although it is not a malignant lesion, a cholesteatoma
can destroy the temporal bone and cranium and cause signicant complications.
19.2 Definition
A cholesteatoma is an accumulation of desquamated squamous epithelium, also
called “skin in the wrong place,” covered with multilayered squamous epithelium
on a brous matrix and trapped in a sac-like cystic structure. When the words that
form the term reveal that the terminology is awed (chole: bile, stearin: fat, oma:
tumor). The term was rst proposed by Johannes Muller in 1838, who stated that the
lesion was a fatty tissue tumor [3]. However, it has been shown that there is no fat
or cholesterol involved in these lesions. Since a cholesteatoma does not contain
M. Tan (*)
Faculty of Medicine, Department of Otorhinolaryngology, Inonu University, Malatya, Turkey
S. Turgut
Department of Otorhinolaryngology, Sisli Etfal Training and Research Hospital, Health
Science University, Istanbul, Turkey
E. di Martino
ENT Department, DIAKO Ev, Bremen, Germany
e-mail: e.dimartino@diako-bremen.de
© The Author(s), under exclusive license to Springer Nature
Switzerland AG 2024
M. T. Kalcioglu et al. (eds.), Otology Updates, Comprehensive ENT,
https://doi.org/10.1007/978-3-031-76173-7_19
381
382
cholesterol or lipids, it may be more accurate to call it a keratoma. However, it is
also possible to confuse this term with keratosis obturans, which progresses with the
formation of keratinous debris in the external auditory canal. There are several denitions of cholesteatoma in the literature. Gray dened cholesteatoma as epithelial
debris in the wrong place [4]. Although cholesteatoma is not an accurate term, it has
been used by otolaryngologists to this day. Cholesteatoma, which can be congenital
or acquired, has not lost its relevance due to unanswered questions and has maintained a place in the literature as a topic of ongoing research.
M. Tan et al.
19.3 Epidemiology
The incidence of cholesteatoma varies by region, country, age, gender, genetic, and
socioeconomic factors. It has been demonstrated that 20 million people worldwide suffer from chronic otitis media and one quarter of these people have cholesteatoma. It has
been found that while the annual incidence of cholesteatoma in the pediatric population
is 3in 100,000, this rate is 9.2in 100,000in the adult population [5]. One study showed
that 10–17% of patients with cholesteatoma had contralateral ear involvement [6]. When
comparing pediatric cholesteatoma with adult cholesteatoma, it was reported that pediatric cholesteatoma caused more ossicular destruction and spread more into the middle
ear and mastoid, but the complication rate was higher in adults. The researchers linked
this to the fact that children are brought to health care facilities by their parents earlier
[7]. Cholesteatomas are more common in males than females by a ratio of 1.4:1, and
middle ear cholesteatomas are more common in patients younger than 50years [8]. Its
prevalence is high in the Caucasian population, but it is rarely seen in Indian and Asian
populations. It has been reported that while primary acquired cholesteatoma is more
common in the Caucasian race, secondary acquired cholesteatoma is more common in
Asia with a higher risk of complications [9]. One study reported that the incidence of
cholesteatoma was higher in patients of lower socioeconomic level [10]. A review of the
literature suggests that the formation of retraction pockets in the tympanic membrane
decreases with age and that this is due to increased Eustachian tube function. Compared
to children with cleft palate who have Eustachian tube dysfunction, cholesteatoma has
been found to be 100–200 times more common in patients with cleft palate [11]. In a
study, it has been revealed that those who have a family member with cholesteatoma are
under four times more risk compared to those who have no family members with cholesteatoma [12]. It is known that atelectasis is a factor that prepares the ground for the
development of cholesteatoma and that the ventilation tube placed on the tympanic
membrane reduces this atelectasis.
19.4 Histopathology
Regarding the histopathology of cholesteatoma, the cystic core containing keratinous debris is composed of the matrix, which generates keratinous tissue and contains squamous epithelium, and the perimatrix layers, which contain subepithelial
19 Cholesteatoma
383
connective tissue. The content of the cyst is the primary component of the cholesteatoma. It consists of a fully differentiated keratinous slough mixed with sebaceous
and purulent and/or necrotic material.
The matrix of the cholesteatoma consists of a multilayered squamous epithelium. The cholesteatoma epithelium, like the skin, contains a basal layer (stratum
germinativum), a spinal layer (Malpighian), a granular layer, and a clear layer. The
germinative layer, called the matrix, is a keratinized Malpighian epithelium and sits
on the chorionic layer, which is reinforced by connective tissue. In cholesteatoma
surgery, it is necessary to clean the matrix, and only removal of the cholesteatoma
leads to recurrence of cholesteatoma. Dead cell layers are arranged in layers of different thicknesses in the matrix. In this respect, a cholesteatoma can be compared to
the layers of an onion. From the matrix to the center, this layer order is disrupted and
melting occurs in the center. The center of a cholesteatoma is amorphous and sometimes infected. As the infection progresses, dead cells decompose and a foul odor
develops. In this case, granulation tissue appears in the matrix area. The outermost
layer is the perimatrix, which is an infected subepithelial connective tissue (granulation tissue) containing inammatory cells such as collagen bers, brocytes and
lymphocytes, plasma cells, histiocytes, and neutrophils (lamina propria).
Inammatory mediators released from the perimatrix layer led to bone destruction
due to factors such as activated metalloproteinase enzymes and the bulk pressure
created by cholesteatoma.
19.5 Biology ofCholesteatoma
Although a cholesteatoma is a hyperproliferative reaction, it is not a tumor. It does
not metastasize and there is no genetic imbalance involved. It is a disease process
involving inammatory cytokines, stimulation of growth factors and bacterial toxins, and internal molecular dysregulation. It is the comorbidity of uncontrolled epithelial proliferation and inadequate self-cleaning. Bacteria colonizing the retraction
pockets create a vicious cycle by triggering cytokine activities [13]. Activated
osteoclasts lead to bone destruction and disease development. Uncontrolled immune
system activity in immunohistochemical studies triggers disease in acquired cholesteatoma. Endotoxin on the cell walls of bacteria triggers inammation in the middle
ear and retraction pocket. This triggers local macrophages and leads to the production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta).
Keratinocytes are stimulated and lead to the production of many mediators such as
TNF-α, IL-1β, IL-6, and IL-8 [14]. As a result of this stimulation, active keratinocytes proliferate and the formation of an epithelium surrounded by granulation tissue is observed [15].
The exact cause of proliferation in cholesteatoma tissue is not understood.
Cytokines induced by chronic inammation led to intense inltration of immune
cells. Chronic infection, granulation tissue, and hyperproliferating keratinocytes
result in persistent immune system activity. Mast cells, active T cells, and macrophages are frequently seen in cholesteatoma [16, 17].
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M. Tan et al.
Proinammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha)
and interleukin-1 alpha (IL-1 alpha) play an important role in the development
of cholesteatoma and subsequent complications. TNF-alpha is one of the major
cytokines involved in the pathophysiology of cholesteatoma. When measured in
a cholesteatoma specimen, it was found to be elevated compared to the external
ear canal. TNF-alpha levels correlate with the degree of bone destruction, infection, and inammatory cell counts [18]. This mediator is secreted by active
macrophages, keratinocytes, and mast cells. IL-1 (both IL-1α and IL-1β) levels
are elevated in cholesteatoma specimens. Although difcult to correlate with
bone destruction, elevated cytokine levels have been observed in cholesteatoma
specimens. Other enzymatic reactions are responsible for the destructive effect
of cholesteatoma. Recent studies have shown that the production of cellular
matrix metalloproteinases (MMPs) contributes to the pathology. It has been
shown that excessive expression of MMP-9 and to a lesser extent, MMP-2 may
play a role in the molecular mechanisms of cholesteatoma invasion and bone
destruction [19].
19.6 Etiopathogenesis andClassification
There have been countless controversies regarding the classication of cholesteatoma and it has been divided into two main types as acquired and congenital cholesteatoma. Congenital cholesteatoma develops behind the healthy tympanic membrane
and is often seen in children who do not have a history of chronic otitis. Acquired
cholesteatomas are divided into two groups: primary and secondary acquired
cholesteatomas.
The primary group is usually seen in the pars accida and develops as a result of
the accumulation of desquamated epithelium in retraction pockets and its inammation. The underlying pathogenesis is complex.
Chronic Eustachian tube dysfunction plays a central role. In a healthy middle ear
environment, there is a physiological tendency for persistent net gas absorption
resulting in negative pressure. Impaired tube ventilation exacerbates this problem
and promotes the development of tympanic retraction. For pars accida (epitympanal) retraction to occur, the upper posterior-superior airway passage must be
obstructed. This passage has an anterior isthmus between the tensor tympani tendon
and the stapes and a posterior isthmus represented by the posterior incus ligaments
and the surrounding bony wall [20].
Secondary acquired cholesteatomas develop as a result of epithelial migration
from perforated tympanic membranes [21].
In another classication by Tos, otoscopic classication was made according to
the site of origin of the disease, which are attic, pars tensa 1(marginal disease), and
pars tensa 2 (central disease) [22].
Petrous apex cholesteatomas, which are rarely seen, were classied by Sanna
etal. [23] into ve categories: supralabyrinthine, infralabyrinthine, massive labyrinth, infralabyrinthine-apical, and apical.
19 Cholesteatoma
385
In the joint study conducted with the consensus of the European Academy of
Otology and Neurotology and the Japanese Otology Society (EAONO/JOS) in
2017, cholesteatomas were classied into three categories congenital, acquired, and
unclassied [24]. This classication has been widely adopted. In this classication,
acquired cholesteatoma is divided into subcategories. According to this classication, cholesteatoma development is divided into two main headings as: 1) retraction
pocket cholesteatoma and 2) non-retraction pocket cholesteatoma. Retraction
pocket cholesteatomas are divided into three subcategories: a) pars accida cholesteatoma (attic cholesteatoma), b) pars tensa cholesteatoma, and c) cholesteatoma
with a combination of pars accida and pars tensa. Non-retraction pocket cholesteatoma is divided into two subcategories: a) cholesteatoma secondary to perforation
of the tympanic membrane (secondary acquired cholesteatoma) and b) cholesteatoma developing after trauma and/or otologic procedures [24].
Postoperative cholesteatoma may be residual or recurrent.
A middle ear cholesteatoma can be staged according to the STAM system or the
EAONO/JOS staging system. The STAM system divides the middle ear and mastoid cavity into four zones to dene cholesteatoma involvement. These are difcult
access zones (S), tympanic space (T), attic (A), and mastoid (M). Difcult access
sites are the supratubal groove (anterior epitympanum or protympanum) (S1) and
the sinus tympani (S2) [24].
The EAONO/JOS staging system describes four types of middle ear cholesteatoma. These are pars tensa, pars accida, pars tensa, congenital cholesteatoma, and
cholesteatoma due to tensa perforation. If the cholesteatoma is located in the primary area, it is called stage 1. If the cholesteatoma is located in two or more areas,
this is stage II.If cholesteatoma is associated with extracranial complications or
certain pathologic conditions, this is stage III.These pathologic conditions include
labyrinthitis, labyrinthine stula, facial palsy, zygomatic abscess, neck abscess,
postauricular abscess or stula, canal wall destruction, destruction of the tegmen,
and adhesive otitis. If cholesteatoma is associated with intracranial complications, it
is called stage IV.These are; purulent meningitis, subdural abscess, epidural abscess,
sinus thrombosis, brain abscess, and brain herniation into the mastoid cavity [25].
The staging system does not apply to petrous bone cholesteatoma [24].
The EAONO/JOS staging system for middle ear cholesteatoma is widely
accepted. The advantage of this system is that it provides a standardized assessment
of the initial pathology and can be used to standardize the reporting of surgical outcomes in the otology community. However, petrous bone cholesteatoma is not
included in this staging system.
19.7 Cholesteatoma Types
19.7.1 Congenital Cholesteatoma
Congenital cholesteatoma is a growing mass of keratinized squamous epithelium
located medial to the healthy tympanic membrane. There is no history of tympanic
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membrane perforation, retraction pocket, trauma affecting the ear, or ear surgery. It
is usually diagnosed in early infancy or early childhood. The incidence has been
reported as 0.12/100.000. While congenital cholesteatoma constitutes 4–24% of
cholesteatoma seen in childhood, it makes up 2.5% of all cholesteatoma [26].
Congenital cholesteatomas are generally located in the anterosuperior of the middle
ear right above the Eustachian tube, but they can also be located in the posterosuperior quadrant.
In anatomical region classication, congenital cholesteatoma is classied as:
Type 1: Cholesteatoma is limited to the middle ear and only the malleus manubrium
is affected.
Type 2: Cholesteatoma affects the ossicles in the region between the posterosupe-
rior quadrant and the attic.
Type 3: Cholesteatoma has spread to the mastoid.
Type 1 is usually controlled with an endoscopic or transcanal approach and limited intervention. Repeat surgery is usually not required. Type 2 lesions are
approached with an extended tympanotomy but may require attikotomy or tympanomastoidectomy. Sometimes a second look or follow-up with non-epi diffusion
magnetic resonance imaging (MRI) may be preferred. Ossicular reconstruction may
be required due to ossicular involvement. For type 3 lesions, the same approach is
used as for type 2, but sometimes a canal wall down mastoidectomy may be necessary. The frequency of recurrence increases as the lesion progresses from type 1 to
type 3 [27].
The most widely accepted theory of the mechanism of development of congenital
cholesteatoma is the “epithelial remnant theory.” Teed in 1936 and Michaels in 1986
detected an epidermoid remnant in the anterosuperior quadrant of the middle ear of
human fetuses, which Michaels called the epidermoid formation [28, 29]. Normally,
epithelial debris is not detected after 33weeks of gestation and, if present, leads to
the development of congenital cholesteatoma. One study in fetuses showed the presence of epithelial formation in the middle ear [30]. Later studies have demonstrated
epidermoid formation in the ears of infants, children and fetuses [31, 32]. According
to Bennet etal. [33], the presence of epithelial formation does not explain the presence of congenital cholesteatomas outside the anterosuperior quadrant of the tympanic membrane. Congenital cholesteatomas can be found in the posteroinferior,
posterosuperior, and anteroinferior quadrants of the lateral wall of the tympanic cavity, which may explain the insistence on additional theories of formation [34].
Tos stated that there may be other possibilities besides the epithelial remnant
theory. According to Tos’s observations, anterosuperior congenital cholesteatoma
was seen in the anterior manubrium mallei and malleus neck, while posterosuperior
congenital cholesteatoma was seen in the posterior manubrium, malleus neck, and
incudostapedial joint. These regions were far from the anterosuperior quadrant
where epithelial remnants are often seen. However, Tos suggested that a congenital
cholesteatoma may have obstructed the Eustachian tube prior to its formation, and
the collapsed membrane approximated this region [35].
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Tos also proposed a new inclusion theory that could replace the epithelial remnant theory. According to Tos, it is possible that squamous epithelium may be
implanted or included in the middle ear cavity due to certain events that may affect
the tympanic membrane during childhood. Living keratinized epithelium adheres to
the weakened tympanic membrane between the anterior and posterior manubrium
mallei and the neck of the malleus and the incudostapedial joint. As the tympanic
membrane repairs itself, it becomes trapped in the middle ear cavity and can be
included in the middle ear without perforation. This epithelial inclusion causes the
tympanic membrane to retract and touch the ossicles, and the epithelium remains
here [35]. After the tympanic membrane repairs itself, a cholesteatoma may develop
from the keratinized epithelium inside.
Congenital epidermal cysts usually form near the tympanic isthmus of the middle ear, according to topographic studies. This is the region where the primary and
secondary brachial arches meet. Thus, the formation of congenital cholesteatoma
may be related to the embryonic stage and may be due to the migration of ectoderm
from the external auditory canals to the middle ear. Studies suggest that the tympanic ring plays an important role in limiting the medial extension of the external
auditory canal at this level. If this restriction is insufcient, ectodermal tissue may
migrate into the middle ear. Human fetuses have been studied to elucidate this
developmental relationship. In one study, mesenchymal papillary ectodermal tissue
was shown to be prominent near the tympanic isthmus. In these fetuses, the distance
between the inner ear canal and the tympanic ring was reported to be very short
[36]. This observation suggested that cholesteatoma may be the result of ectodermal
migration [37].
Clinic
It may obstruct the Eustachian tube and secondarily lead to serous otitis media. In
the early stages, a congenital cholesteatoma may appear as a slight whitish color
change or as a round, white cyst behind a normal-appearing tympanic membrane.
Over time, it lls the middle ear volume and may cause the tympanic membrane to
bulge outward. Tympanic membrane perforation and otorrhea are symptoms seen in
later stages. It usually spreads toward the medial side of the ossicles, causing conductive hearing loss. The growth usually occurs posteriorly and inferiorly.
Development from the inner side of the ossicles towards the hypotympanum is
another common type. It primarily involves the posterior mesotympanum and the
incudostapedial joint, but usually the stapes base is free. Involvement of the facial
nerve is more common. It then extends to the facial recess, the tympanic sinus, and
the aditus. Involvement of the otic capsule and invasion of the labyrinth are rare.
The average age at diagnosis is 4–5years. Recurrent otitis media at this age is a
warning of congenital cholesteatoma.
As the mass expands, symptoms begin to appear. Conductive hearing loss is a
common symptom. In fact, it is diagnosed in children who are brought in for evaluation of hearing loss. In posterior development, conductive hearing loss is more
common, and in anterior development, tympanic membrane retractions due to
Eustachian tube obstruction are more common. Otalgia and otorrhea are rare, but a