2 Diagnosis of Cholesteatoma



10.1055/b-0039-169406

2 Diagnosis of Cholesteatoma


Cholesteatoma is an epidermal inclusion cyst localized in the middle ear, whose capsule and matrix is formed from stratified squamous epithelium. The desquamating debris includes pearly white lamellae of keratin that accumulate concentrically, forming the cholesteatoma mass. The term cholesteatoma is actually a misnomer. It is derived from the Greek words “chole” or bile, “steatos” or fat, and “oma” or tumor. There is no relation between cholesteatoma and bile or fat. The suffix “oma” (tumor), however, is more appropriate because cholesteatoma can be considered an epidermal inclusion cyst forming a tumor in the ear. Fetid otorrhea and hearing loss are the main complaints in most of cholesteatoma patients. In addition, complicated cases can manifest with vertigo and/or facial nerve paralysis. Vertigo occurs as a result of labyrinthine fistula, which is most commonly located in the lateral semicircular canal. Facial paralysis can be caused by pressure of the cholesteatoma sac or neuritis.


The most important finding for diagnosing cholesteatoma is usually obtained in micro-otoscopy in the outpatient clinic. Clue for diagnosis may be scant, such as a very small erosion in the pars flaccida, or small whitish mass behind the tympanic membrane. Therefore, it is essential to carefully check the entire tympanic membrane using either a microscope or an endoscope if patients visit with some otologic complaints. We prefer to use an endoscopy in the outpatient clinic, since it gives a picture of the entire tympanic membrane even if there is a tight curve in the meatus. If presence of cholesteatoma is diagnosed or speculated, radiological examination with high-resolution computed tomography (CT) is indicated. The thickness of each slice should be less than 1 mm to visualize middle ear structures. Even though CT is not able to discriminate cholesteatoma from other soft tissues and effusions, it gives abundant information regarding extension of the disease and bony erosions that serves for surgery. If there is any doubt of meningoencephalic herniation or extension to the petrous apex, magnetic resonance imaging (MRI) is indicated. The MRI gives excellent contrast between cholesteatoma and other soft tissues when proper modality is applied. Since diffusion-weighted modality gives high signal in cholesteatoma, it is also useful for detection of residual lesion after tympanoplasty and subtotal petrosectomy. In cases of petrous bone cholesteatoma, otoscopy may be irrelevant or only demonstrates pars flaccida perforation or an open mastoid cavity with evidence of otorrhea. When a patient presents with hearing loss (sensorineural or mixed) and/or facial nerve paralysis with or without a retrotympanic mass, the possibility of petrous bone cholesteatoma (PBC) should be considered. The MRI is fundamental to evaluate such cases. Once petrous bone cholesteatoma is identified, it is necessary to perform a high-resolution CT scan of the temporal bone to evaluate extension of the cholesteatoma.


The PBCs are locally aggressive, and may extend to the clivus, nasopharynx, sphenoid sinus, the infratemporal fossa, and intradural compartment.


Regarding the source of the squamous epithelium, cholesteatoma can be classified into two types: acquired and congenital (▶Table 2.1); the acquired ones are much more common than the congenital ones, comprising the majority of surgical cases.


In acquired cholesteatoma, the squamous epithelium originates from the skin covering either the tympanic membrane or the external auditory canal. The acquired ones can be divided into two categories: primary and secondary. The primary cholesteatoma is formed from a retraction pocket that becomes so deep that keratin debris can no longer be expelled, leading to its accumulation and subsequent cholesteatoma formation. Cause of such retraction is not known fully, but dysfunction of the eustachian tube related to some infectious condition, such as sinusitis, allergy, and otitis media, seems to play a key role. Such retraction pockets often remain asymptomatic until they become infected, resulting in otorrhea and hearing loss. In some cases, the only symptom might be a progressive hearing loss due to erosion of the ossicular chain. The primary cholesteatomas are subclassified according to its initial localization. The pars flaccida (or epitympanic) type originates from the pars flaccida that seems more susceptible to negative pressure in the middle ear. The pars tensa (or mesotympanic) type is less frequent, originating from the pars tensa of the tympanic membrane, usually the posterosuperior quadrant. Since it erodes the incudostapedial joint from the beginning, patients are likely to present with considerable hearing loss. In cholesteatoma of the external auditory canal, destruction of the temporal bone starts from the external auditory canal, and inflamed skin with debris infiltrates the middle ear. Different from the former two types, ischemic condition of the bone is speculated to play a key role. Secondary cholesteatoma is formed by the skin advanced into the middle ear through a disrupted barrier formed by the tympanic membrane and the skin in the external auditory canal. The disruption occurs in a chronic perforation of the tympanic membrane, that is, chronic otitis media. Marginal perforations and tympanosclerosis increase risk of the skin crossing the border. Medical intervention can tuck the squamous epithelium into the middle ear. Such procedures include myringotomy, insertion of the ventilation tube, and tympanoplasty. The tuck of the skin also occurs in traumatic tympanic membrane perforation and temporal bone fracture.













































Table 2.1 Categorization of cholesteatoma PBC

Source of skin


Subclassification


Localization or cause


Termed


Acquired


Primary


Pars flaccida (epitympanic)



Pars tensa (mesotympanic)


External auditory canal


Secondary


Chronic otitis media


Iatrogenic


Traumatic


Primary or secondary


Medial to labyrinth


PBC


Congenital




Middle Ear


(Congenital)


Abbreviation: PBC, petrous bone cholesteatoma.


Congenital cholesteatoma is speculated to be derived from entrapped ectodermal cellular debris during embryonic development. When it involves the middle ear, it appears as a whitish retrotympanic mass that may be localized either anterior or posterior to the malleus. In rare cases, cholesteatoma may arise in some part of the temporal bone away from the tympanic membrane. In such cases, the tympanic membrane seems intact, or the only indication is presence of middle ear effusion. In such cases, the lesion may be recognized in radiological examinations performed after some neurological symptoms appear, or only by chance.


When cholesteatoma involves the petrous part of the temporal bone that is medial to the labyrinth, it is termed petrous bone cholesteatoma. The source of the skin can be either congenital or acquired, as a consequence of advanced lesion. Because of its localization, the petrous bone cholesteatoma can invade the labyrinth, cochlea, posterior and middle fossa dura, the internal auditory canal, and the petrous apex, and may cause various neurological symptoms and life-threatening conditions.



2.1 Epitympanic Retraction Pocket


It is not always easy to establish a clear distinction between epitympanic or posterosuperior retraction pockets and cholesteatoma (see ▶Fig. 2.1 and ▶Fig. 2.2). We prefer to follow up these patients with otomicroscopy and endoscopy. A 30-degree endoscope is useful to see clearly the bottom of the retraction. Radiological examination using high-resolution CT may give additional information regarding the safety of the retraction. If the retraction pocket becomes deep, or accumulation of debris starts, a tympanoplasty is indicated. Because of the early stage of the disease, surgery can be done in a single stage.

Fig. 2.1 Right ear. A deep pocket is identified in pars flaccida. Even if the CT scan did not show an apparent cholesteatoma, occasional otorrhea forced the patient to undergo surgery (closed tympanoplasty with attic reconstruction with cartilage and bone paste). No cholesteatoma was found in the mastoid.
Fig. 2.2 Left ear. Deep epitympanic erosion extended to the posterior epitympanum. The neck of the malleus and the body of the incus are under view. The chorda timpani is also evident. The patient did not suffer from otorrhea or hearing loss, but a strict follow-up should be assessed to avoid further development of a cholesteatoma.


2.2 Epitympanic Cholesteatoma


The epitympanic cholesteatoma is the most frequent form of acquired cholesteatoma. The cholesteatoma arises from an epitympanic retraction pocket as described above, and usually does not cause any symptom until it gets infected, interrupts the ossicular chain, erodes the labyrinth, or injure the facial nerve (see ▶Fig. 2.3, ▶Fig. 2.4, ▶Fig. 2.5, ▶Fig. 2.6, ▶Fig. 2.7, ▶Fig. 2.8, ▶Fig. 2.9, ▶Fig. 2.10, ▶Fig. 2.11, ▶Fig. 2.12, ▶Fig. 2.13, ▶Fig. 2.14, ▶Fig. 2.15, ▶Fig. 2.16, ▶Fig. 2.17, ▶Fig. 2.18). Most of them can be diagnosed by careful otoscopic inspection. Therefore, it is definitely prohibited to say “OK” to the patient who is complaining ear problems after seeing only the easy-to-access pars tensa. In very rare cases, the orifice of cholesteatoma can be obscured with a re-epithelized granulation tissue covering the pars flaccida. Since only radiological examinations give definitive clue, high grade of suspicion with knowledge is required to diagnose such cases.


In some cases, invagination of the skin in the pars flaccida and the pars tensa coexist, or extend to each other making categorization of primary cholesteatoma into two not possible. The situation can be called epimesotympanic cholesteatoma.

Fig. 2.3 Left ear. Epitympanic cholesteatoma in a 20-year-old man in the only hearing ear. The whitish cholesteatoma mass is visible anterior to the malleus (arrow). This is an example on how an epitympanic pocket can progressively led to a cholesteatoma. This patient has undergone removal of a right petrous bone massive cholesteatoma (for definition and classification see Chapter 10) through a transotic approach 5 years before. The left epitympanic retraction pocket (see ▶Fig. 8.9) was followed up until the evidence of a cholesteatoma. The patient did not complain of any symptom on the left ear and hearing function was normal. Considering the small size of the cholesteatoma, a left closed tympanoplasty was performed with preservation of the whole ossicular chain (see ▶Fig. 8.12, ▶Fig. 8.13, ▶Fig. 8.14, ▶Fig. 8.15, ▶Fig. 8.16). A detailed description of the steps of open and closed tympanoplasties will be provided at the end of the chapter.
Fig. 2.4 Same case. Otoscopy performed 1 year before that in ▶Fig. 2.3. A small controllable anteromalleolar epitympanic retraction pocket is visible (arrow). Considering that it is the only hearing ear surgery is questionable at this stage, but a strict follow-up is mandatory because early detection of a cholesteatoma is crucial for a correct management and outcome.
Fig. 2.5 CT scan of the same case, coronal view. A small epitympanic cholesteatoma is visible (arrow).
Fig. 2.6 Left ear. Epitympanic cholesteatoma. The head of the malleus and the body of the incus are visible. The inferior and posterior quadrants of the tympanic membrane are tympanosclerotic. The cholesteatoma was lateral to the ossicular chain (see ▶Fig. 2.10). Hearing function was normal. A modified Bondy technique open tympanoplasty was performed and no recurrence of cholesteatoma occurred during the follow-up.
Fig. 2.7 CT of the same case, coronal view. The cholesteatoma is limited in the epitympanic area (arrow), lateral to the head of the malleus. The mesotympanum is free of disease. The case can be a complete indication of modified Bondy technique.
Fig. 2.8 Epitympanic cholesteatoma with erosion of the head of the malleus and the incus. The cholesteatoma descends to the tympanic cavity (black arrow) to contact with the stapes. The head of the stapes is adherent to the tympanic membrane (red arrow: myringostapediopexy) resulting in normal hearing. The rest of the tympanic membrane is slightly retracted due to obstruction of the eustachian tube. Possibility of postoperative hearing deterioration has to be informed preoperatively.
Fig. 2.9 Large epitympanic erosion with cholesteatoma. Audiometry showed moderate conductive hearing loss.
Fig. 2.10 CT scan of the same case, coronal view. Epitympanic cholesteatoma with erosion of the head of the malleus (yellow arrow) and thinning of the tegmen tympani (white arrow).
Fig. 2.11 CT scan of the same case, coronal view. The long process of the incus and stapes superstructure are eroded by the cholesteatoma.
Fig. 2.12 CT scan of the same case, axial view. The cholesteatoma extends posteriorly toward the antrum and the mastoid (arrow). However, some of the opacification may be effusion and scar tissue. Incapability to discriminate soft tissue is one of the drawbacks of CT examination.
Fig. 2.13 Another case of epitympanic cholesteatoma. A deep erosion with debris involving the head of the malleus and the body of the incus is present in the attic.
Fig. 2.14 CT scan of the same case, coronal view. Epitympanic cholesteatoma severely erodes the short process of the incus.
Fig. 2.15 Left ear of the same patient. Cholesteatoma with marked erosion of the scutum and epidermization of the attic and mesotympanum. The cholesteatoma debris was partially cleaned. The residual pars tensa shows tympanosclerosis. Intraoperatively, the ossicular chain was absent. The otoscopic view of the left ear is apparently more advanced than the right ear. This, however, was not the case intraoperatively since the marked epitympanic erosion shown here allowed self-cleaning of the cholesteatoma debris (see CT scan, ▶Fig. 2.16). Because of the total destruction of the ossicular chain, a second stage was programmed for functional reconstruction.
Fig. 2.16 CT of the same case showing cholesteatoma extension in the mastoid in the right ear and self-cleaning of the cholesteatoma debris in the left ear (arrows).
Fig. 2.17 Left ear. Cystic retrotympanic cholesteatoma situated posterior to the malleus. The tympanic membrane shows bulging at the level of the pars flaccida and slight retraction with tympanosclerosis in the posterior quadrants. Since debris is covered, inattentive observation may overlook presence of cholesteatoma.
Fig. 2.18 Same case as in ▶Fig. 2.17 during an acute inflammatory episode. Note the increase in size of the cholesteatoma.

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May 12, 2020 | Posted by in OTOLARYNGOLOGY | Comments Off on 2 Diagnosis of Cholesteatoma
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