Chapter 14

Congenital cholesteatoma of the ear is cholesteatoma developed behind an intact tympanic membrane when there is no history of aural infections. House1 first reported congenital cholesteatoma in 1953. In 1963 Cawthorne² postulated the congenital origin of some cholesteatomas, citing from a single case. Derlacki and Clemis³ proposed the clinical criteria for the diagnosis in 1965. House and Sheehy⁴ advocated a surgical approach for management of congenital cholesteatomas in 1980.

ORIGIN

Congenital cholesteatoma is thought to be of embryologic origin and many theories were proposed to explain the different clinical presentations. Cushing⁵ suggested that many of the cholesteatomas reported by otologists were likely true dermoids originating from epidermal rests laid down in the temporal bone during embryologic development of the ear. Depending on the location of the epidermal rests, cholesteatomas may appear in the middle ear, the mastoid region, the petrous pyramid, and the cerebellopontine angle (CPA). Congenital cholesteatoma of the middle ear is the most common type. The squamous epithelial mass is found in the anterosuperior quadrant of the tympanum at the junction of the mucosa of the eustachian tube and the mucosa of the middle ear, which is the reported site of the embryologic epithelial rest. Sanna and Zini⁶ suggested that congenital middle ear cholesteatoma arose from epidermal cells trapped in the posterior mesotympanum during embryologic de-velopment. This explains why the posterior mesotympanum is where congenital cholesteatoma is the most commonly presented.

Paparella and Rybak⁷ proposed that ectodermal implants occurred in the fusion planes of the first and second branchial arches, which resulted in the development of epidermoid in the middle ear and other areas of the temporal bone. Michaels⁸ theorized that the epidermoid formation appears early in embryonic life arising from the ingrowth of ectodermal cells from the first branchial groove, where it joins the first pharyngeal pouch. At this early primal stage of development, ectoderm and endoderm of the groove and pouch lie in close proximity to each other without intervening mesenchymal cells. Then the epidermoid formation precursor buds off from the first groove ectoderm and takes a position attached to the pharyngeal pouch.

Aimi⁹ proposed that congenital cholesteatoma occurs in the middle ear because of migration of external canal ectoderm during middle ear development. Under normal circumstances the tympanic ring inhibits or restricts ingrowth of ectoderm from the external canal into the middle ear. Should this mechanism fail, migration of keratinizing epithelium into the middle ear might result in the formation of a congenital cholesteatoma.

Weber and Adkins¹⁰ reported three cases of congenital cholesteatoma in the tympanic membrane. The authors postulated the squamous epithelial basal layer proliferation as a cause for intramembranous cholesteatoma of the tympanic membrane. If treatment is delayed, the cholesteatoma may extend into the middle ear.

PATIENT PRESENTATION

Congenital cholesteatoma is usually noted in young children. It is more common in males, with a near 3:1 preponderance in several reports.^11–13 The mean age of presentation is 4.5 years.11–13 Doyle and Luxford¹⁴ reported 60 cases of congenital cholesteatomas. In 24 patients, cholesteatoma was limited to the mesotympanum, 18 ears had cholesteatoma located in both the mesotympanum and epitympanum, and two patients had disease limited to the epitympanum. In 16 ears, there was extensive cholesteatoma in the mesotympanum, epitympanum, and mastoid. Classically there is no prior history of otorrhea, perforation, or otologic surgical procedures. Preoperative symptoms and signs are predominantly conductive hearing loss. Frequently, when the cholesteatoma is small, it is asymptomatic and is often discovered incidentally. Because of the silent nature of this lesion, the patient may not notice until symptoms of complication occur, such as facial nerve paralysis and intracranial extension. Landers and May¹⁵ reported a case with facial palsy caused by a preauricular cyst associated with congenital cholesteatoma. Rapoport et al¹⁶ reported a huge congenital cholesteatoma simulating an intracranial abscess.

Congenital cholesteatoma may occur in five sites within the temporal bone: (1) the tympanic membrane, (2) the middle ear, (3) the mastoid, (4) the petrous apex, and (5) the CPA. The mode of presentation of congenital cholesteatoma differs according to the site.

Congenital cholesteatoma within the tympanic membrane demonstrates a whitish appearance or an opaque patch on the eardrum. Hearing may not be affected or may show mild conductive hearing loss. An intratympanic cholesteatoma or patch of tympanosclerosis, when viewed binocularly, can be within or lateral to the tympanic membrane.

Congenital middle ear cholesteatoma most commonly presents as a white pearl-like structure behind the anterosuperior portion of a normal intact eardrum. Conductive hearing loss is often the first sign due to ossicular chain damage. Facial nerve palsy is also reported. Rare presentations, however, are also possible. Reilly¹⁷ reported a case that presented as a postauricular mass. Differential diagnosis needs to be performed when a white lesion presents behind the eardrum.

Two histologic types of congenital cholesteatoma, open and closed, have been described.^18,19 The closed type is more frequent and essentially is a closed epithelial cyst. The open type involves the middle ear more diffusely and carpets the middle ear cleft with matrix and keratin debris. Both types are found in the anterosuperior quadrant of the tympanum.²⁰

The majority of white lesions developing behind an intact tympanic membrane are either congenital or acquired cholesteatoma. A congenital cholesteatoma that arises from epithelial cell rests in the lateral part of the middle ear and will appear to be immediately adjacent to and in contact with the tympanic membrane. Well-developed air cells in the mastoid are often seen in congenital cholesteatoma. Most acquired cholesteatoma presents as a retraction pocket or perforation at the pars flaccida with sclerotic mastoid. A bony structure, such as an osteoma arising from the promontory or annulus may present as white lesion behind an intact tympanic membrane. But these lesions will be deep to the tympanic membrane.

Congenital cholesteatoma originating in and restricted to the mastoid process is the least common type.²¹ The initial presentations are a fistula in the external auditory cannel, conductive hearing loss, and neck pain.²² Due to its space-occupying effect, it may compress the cerebellum and the dural sinuses adjacent to it or erode the bony labyrinth. Cureoglu et al²³ reported a case of congenital cholesteatoma originating in the mastoid process and presenting as a mass that extended to the posterior fossa.

Petrous apex cholesteatoma appears in the petrous pyramid near the internal auditory canal. Early symptoms of a mass primarily arising within the petrous apex are usually nonspecific and poorly localized. Petrous apex cholesteatoma results in slow destruction of structures in and around the temporal bone. Most patients are not diagnosed until more localized symptoms appear. Gradual expansion at the petrous bone results in erosion of the adjacent carotid canal. Cholesteatoma may break into the internal auditory canal and damage the auditory and facial nerves. The semicircular canal and cochlea may be eroded, resulting in sensorineural deafness and loss of vestibular function. Nager²⁴ considered that the origin is aberrant neuroectodermal tissue.

The predominant symptoms of congenital cholesteatoma of the CPA were related to cranial nerves VII and VIII and headaches.²⁵ Signs and symptoms were divided into those caused by local involvement of the cholesteatoma, increased intracranial pressure, or both. Facial weakness/paralysis, hearing loss, tinnitus, dizziness, imbalance and headache were the most frequent symptoms. Pulec²⁶ reported that facial nerve twitch, hemifacial spasm, and progressive facial paralysis occurred in 15 of 19 patients. Hearing loss, tinnitus, and vertigo at some time in the course of the disease were present in all 19 cases. Pain and otorrhea occurred in six patients and were invariably associated with infection of the cholesteatoma.

Bilateral lesions are rare, affecting approximately 3% of congenital cholesteatoma patients.²⁷ These lesions may not present at the same time, and long-term follow-up should always include careful scrutiny of the normal ear. The finding of nearly identical lesions in each ear gives further support to a congenital etiology from similar epithelial rests.28 Suetake et al²⁹ reported a case with cholesteatoma on both sides accompanied by ossicular anomalies with hypoplasia of the long process of incus and the superstructure of the stapes. Litman et al³⁰ reported a case of bilateral congenital cholesteatoma with middle ear effusion. Worley et al³¹ reported bilateral congenital cholesteatoma in patients with branchiooto-renal syndrome.

PREOPERATIVE EVALUATION

After careful otoscopic and otomicroscopic examinations are performed, the appearance of the lesion in its quadrant of presentation with respect to the tympanic membrane is noted and sketched. The criteria for diagnosing the congenital cholesteatoma are reviewed, which include (1) the cholesteatoma must be present behind an intact tympanic membrane, (2) the patient must have no history of aural infections, and (3) the patient must have no history of tympanic membrane perforation or surgery.⁵ Audiology evaluation, including complete audiometric and impedance tympanometric studies, is performed. Radiologic studies, including noncontrast high-resolution computed tomography (CT) scanning, and magnetic resonance imaging (MRI) with special attention to the middle ear and mastoid are of value in diagnosing and managing congenital cholesteatoma.

AUDIOLOGY EVALUATION

Pure tone audiogram and speech discrimination are performed to determine the hearing level and the type of hearing loss. Hearing level is related to ossicular chain integrity, and that in turn is a function of patient age and the degree to which the cholesteatoma has extended beyond the anterosuperior middle ear quadrant. Hearing is normal in those patients whose lesion is restricted to the anterosuperior quadrant, unless the lesion has extended posteriorly with involvement of the stapes superstructure or the lenticular process of the incus. Even with ossicular erosion, however, the hearing may be normal, because the cholesteatoma may serve to complete the ossicular chain. In some cases the cholesteatoma has reached sufficient size to block the eustachian tube, in which case a middle ear effusion and a mild conductive hearing loss may be present. Posterior-superior quadrant lesions are much more likely to present with hearing loss initially and are almost always found to have ossicular damage. Impedance tympanometry shows low compliance due to the cholesteatoma mass behind the anterosuperior portion of a normal intact eardrum. Negative pressure increases when cholesteatoma block the eustachian tube. Stapedial reflex usually is absent in ears with middle ear pathology.

RADIOLOGY EVALUATION

The diagnosis of congenital cholesteatoma is usually made on otologic examination including otoscopic and microscopic study of the tympanic membrane. Radiologic studies, including CT scanning, and MRI, however, not only are indicated for diagnostic purposes but also are valuable in assessing the extent of the disease and the degree of bony involvement. CT can delineate the size of the cholesteatoma (Fig. 14–1), demonstrating bone erosion and smooth bone expansion associated with or without soft tissue mass. In some cases, the inferior margin of the lateral attic wall remains intact in congenital middle ear cholesteatoma in the early stage. Erosion of the tegmen, labyrinth, sigmoid sinus plate, facial nerve canal, and ossicles can be best evaluated on CT scans. Both congenital cholesteatoma and cholesterol granuloma of the petrous bone demonstrate erosion and expansion of bone, which cannot be differentiated from each other on CT scans. However, cholesteatoma appears on MRI as hypointense lesions on T1-weighted (T1W) images and hyperintense lesions on T2-weighted (T2W) images. Cholesterol granulomas are seen as homogeneously hyperintense lesions on both on T1W and T2W scans. Mafee³²

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