Differential Presentation of Congenital Cholesteatoma in Twins with Atypical Location

Introduction

Congenital cholesteatoma (CC) of the middle ear is a very rare pathology with no inflammatory process more frequently affecting boys.¹ In identical twins, it can be described as rarest of rare occurrence. CC is an epidermoid cyst that develops behind an intact tympanic membrane (TM) in a patient with no history of otorrhea, trauma, or predisposing ear surgery. It is believed to occur due to straying remnant of embryonic epithelial tissue left after closure of the neural groove, which occurs between the third and fourth weeks of embryonic life.² Derlacki and Clemis³ first defined this condition in 1965, with a modification introduced in 1986 by Levenson et al.⁴ The strict initial criteria were the presence of a white pearl behind an intact TM with no history of perforation, otorrhea, and otologic surgery. It is now accepted that cases with a history of acute otitis media, otitis media with effusion (OME), revealing otorrhea, or myringotomy should be included.²

In a study by Michaels⁵ in the fetal temporal bones, he demonstrated an epidermoid structure between 10 and 33 weeks of gestation located in the anterosuperior part of the tympanum.

The persistence of this Michaels⁵ structure could act as an anlage and lead to CC in the anterior mesotympanum. CC in a child could be asymptomatic and diagnosed incidentally. It could present as hearing loss due to erosion of the ossicular chain or as recurrent attacks of OME due to occlusion of the tubal orifice by the cholesteatomatous mass. Asymptomatic CC could silently progress involving the mastoid space or causing TM perforation.²

Congenital cholesteatoma can lead to vertigo (if semicircular canals are eroded), fever, and headache due to intracranial complications. Facial palsy or sudden sensorineural hearing loss occur as result of progress of CC of the middle ear into petrous bone cholesteatoma (PBC). Otoscopy is characterized by pearly white mass bulging of the anterosuperior or posterior quadrant medial to an intact TM.²

The pediatrician or otologist should have high degree of suspicion to detect the presence of CC at early stage. In this article, we present CC occurring in identical twins in the same side ears (left)—an occurrence reported only once previously in the world literature. However, it is the first case report to our knowledge with atypical location involving the posterior mesotympanum.

Case Reports

Case 2

The brother of the first twin, also 7-year-old boy (second twin), was brought to the otology clinic by the informant (parent) anxious as to whether this child could have similar problem as first twin. The second twin had no prior history of otorrhea or any ENT (ear-nose-throat) procedures in the past. On examination to our surprise, the left ear had retraction of the posterior quadrant of the drum with edema and otitis externa of the deep canal skin. Pediatric audiometry showed normal audiogram but with left B type impedance curve with absent stapedial reflexes. He was treated with topical antibiotics for 1 month, and at follow-up the audiogram was normal again. However, otoscopy showed a white mass in the posterior quadrant behind intact TM.

High-resolution computed tomography showed soft tissue opacification of the left middle ear around the incus and the stapes with involvement of left mastoid air cells. We advised mastoid exploration of the left ear. One month later when second twin came for surgery, the audiologic data were recorded and preoperative mean air-bone gap (ABG) was 47.5 dB.

The second twin underwent canal wall up mastoidectomy with atticotomy. The incus was eroded and removed; stapes suprastruture was intact and normal. Cholesteatoma sac involving the mastoid and posterior mesotympanum was excised into to. Reconstruction was done with Silastic, fascia, and cartilage. Postoperatively, the mean ABG at 3 months was 55 dB with normal TM, and second-look surgery was advised for hearing restoration. One year later, the child underwent second-look surgery with type 2 ossiculoplasty and an epithelial pearl around stapes footplate was removed. The mean postoperative ABG after 5 years of follow-up is 42.5 dB with an improvement of 13.5 dB after second-look surgery. Both the twins have follow-up of 6 years with no recurrence of cholesteatoma (►Fig. 1).

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Fig. 1

Pre- and postoperative oto-endoscopic pictures with preoperative radiology of twins. (A) First twin’s preoperative oto-endoscopic picture of left intact tympanic membrane with posterior quadrant retraction with CC. (B) First twin’s HRCT of left temporal bone (axial image) showing CC in left posterior mesotympanum. (C) First twin’s recent postoperative oto-endoscopic picture after transcanal excision of CC with 6-year follow up. (D) Second twin’s preoperative oto-endoscopic picture of left intact tympanic membrane with posterior quadrant CC. (E) Second twin’s HRCT of left temporal bone (axial image) showing CC mass in left posterior mesotympanum with incus erosion. (F) Second twin’s recent postoperative oto-endoscopic picture after CWU tympanoplasty with type 2 ossiculoplasty (second stage) with 6-year follow-up.

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Discussion

The prevalence of CC is as low as 2 to 5%. CC may present at any age from infancy to adulthood as typical pearly white mass behind an intact TM.⁶ House and Sheehy⁷ have stated that the possibility of CC should be considered in patients with unilateral conductive hearing loss and without a clear diagnosis of OME, regardless of age. CC may be asymptomatic or alternatively may include conductive or sensorineural hearing loss, aural fullness, tinnitus, vertigo, labyrinthitis, facial palsy, and intracranial complications, depending on the location and extent of the lesion.

The pathogenesis of CC is not clear with multiple theories reported in the literature. Teed noted that failure of involution of an ectodermal epithelial thickening in proximity to the geniculate ganglion medial to the neck of malleus may constitute the CC source.⁸ Also, other etiological hypotheses include a tympanic ring defect, epidermoid formation, epithelial metaplasia, or implantation.⁹

The definition of CC by Derlacki and Clemis³ and later addition by Levenson et al⁴ has been challenged by McGill et al⁹, who have reported that approximately 70% children will have one episode of otitis media. In both our cases, contrary to few studies by Derlacki and Clemis³ (1965) and Levenson⁴ et al, CC were located in the posterior mesotympanum. As no existing theory can truly explain the origin of CC in the posterior location, a strong conjecture can be made that these lesions originate from embryonic epithelial cell rests that are trapped in the posterior mesotympanum during the development of the temporal bone, unlike Michael's⁵ structure that could explain CC in the anterosuperior mesotympanum.²

Zini and Sanna¹ have classified CC into type A (mesotympanic), type B (epitympanic), and type AB (mixed). Type A has been further divided into premalleolar (A1) and retromalleolar (A2). Both the cases in this study belonged to type A2 (retromalleolar). The dilemma faced by the otologist is to convince the parents of asymptomatic young children with CC that the surgical excision is the optimal therapy² (►Fig. 2).

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Fig. 2

Pictorial representation of Zini-Sanna classification of congenital cholesteatoma. A1, premalleolar; A2, retromalleolar; B, epitympanic type; AB, mixed type of congenital cholesteatoma.

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Owing to rapid tissue growth and Eustachian tube dysfunction, cholesteatomas in children have a more aggressive growth pattern relative to adults. Thus, incidence of both residual and recurrent diseases is higher in children compared with adults.² Two main goals of surgery in children include eliminating disease completely to prevent recidivism and recurrence and preserving or restoring hearing. This has been achieved in these identical twins mentioned in our report by timely and appropriate surgical intervention with uneventful follow-up for 6 years. Early surgical intervention, which is the optimal therapy in CC avoids progression of disease and reduces the risk of complications and recurrence.

Conclusion

Congenital cholesteatoma is a rare but aggressive disease, which may be asymptomatic in presentation. High degree of suspicion is required by the otologist to diagnose CC, and atypical location of CC in the posterior mesotympanum is quite common. CC in identical twins can be described as the rarest of rare occurrence. Early surgical intervention avoids progression of CC to involve the petrous bone and prevents complications. The goal of surgery is to avoid recurrence and restore hearing in a child.