Congenital cholesteatoma is defined as an epidermoid cyst that develops behind an intact tympanic membrane in a patient with no history of otorrhea, trauma, or previous ear surgery. Michaels studied fetal temporal bones and demonstrated the presence of an epidermoid structure between 10 and 33 weeks of gestation. This structure tends to involute spontaneously until it completely disappears. Michaels hypothesized that the persistence of this structure could act as anlage and lead to congenital cholesteatoma. The fact that the most classic location of congenital cholesteatoma, namely, in the anterosuperior part of the tympanum, corresponds to the site of the fetal Michaels’ structure supports this theory. In our cases, however, and contrary to the few studies reported in literature (Cohen 1987, Derlacki and Clemis 1965, Friedberg 1994, Levenson et al 1989), the most common site of congenital cholesteatoma was the posterior mesotympanum (see ▶ Table 9.1). As no existing theory can truly explain the origin of congenital cholesteatoma in the posterior location, a strong conjecture can be made that these lesions might represent a different entity from those of the anterior location and may originate from epithelial cell rest that are trapped in the posterior mesotympanum during the development of the temporal bone. Diagnosis is occasional in the asymptomatic patient, or the patient may complain of hearing loss due to erosion of the ossicular chain or of recurrent attacks of secretory otitis media due to occlusion of the tubal orifice by the cholesteatomatous mass. A high degree of suspicion and thorough examination are essential in detecting the presence of these lesions. Refer to ▶ Fig. 9.1, ▶ Fig. 9.2, ▶ Fig. 9.3, ▶ Fig. 9.4, ▶ Fig. 9.5, ▶ Fig. 9.6, ▶ Fig. 9.7, ▶ Fig. 9.8, ▶ Fig. 9.9, ▶ Fig. 9.10, ▶ Fig. 9.11, ▶ Fig. 9.12, ▶ Fig. 9.13, ▶ Fig. 9.14, ▶ Fig. 9.15, ▶ Fig. 9.16, ▶ Fig. 9.17, ▶ Fig. 9.18, ▶ Fig. 9.19, ▶ Fig. 9.20, ▶ Fig. 9.21, ▶ Fig. 9.22, ▶ Fig. 9.23, ▶ Fig. 9.24 Type Location Percent Type A Mesotympanic 52.27 Type A1 Premalleolar 5.55 Type A2 Retromalleolar 46.72 Type B Epitympanic 6.83 Type A/B Mixed 40.90 Fig. 9.1 Type A1 congenital cholesteatoma. Fig. 9.2 Type A2 congenital cholesteatoma. Fig. 9.3 Type B congenital cholesteatoma. Fig. 9.4 Type A/B congenital cholesteatoma. Fig. 9.5 Left ear. Congenital cholesteatoma (type A2) seen as a white retrotympanic mass causing bulging of the posterosuperior quadrant of the tympanic membrane. Neither drum perforation nor bony erosion is detected. In this case, the cholesteatoma caused erosion of the long process of the incus with resultant conductive hearing loss. Fig. 9.6 Right ear. Type A1 congenital cholesteatoma. The cholesteatoma is located in the area of the Eustachian tube, causing middle ear dysventilation and tympanic membrane retraction. Audiometry showed mild conductive hearing loss.
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