INTRODUCTION

Only 2-4% of cholesteatomaspresentingto paediatric otologist are congenital in origin. Disease severity can range from intratympanic pearls to middle ear and mastoid obliteration (Richter & Lee 2009). Derlacki & Clemis (1965)in their article established the clinical criteria for the diagnosis of congenital cholestea­toma (CC). These include a pearly white mass medial to an intact tympanic mem­brane, a normal pars tensa and flaccida, and no previous history of otorrhoea or perforation, or previous otologic proce­dure. Levenson et al. (1986) revised the criteria by adding that previous bouts of otitis media or effusion should not be the exclusion criteria. However, disease se­verity depends on location, patients’ age, ossicular integrity, and number of ana­tomic sites involved. These variables have inspired the development of staging systems whereby appropriate surgical approaches can be designed. Computed tomography is necessary and continue to be the best radiographic tool for surgical planning. Over 30% of CC can be extir­pated through a transcanal approach. Involvement of the posterior quadrant, over three anatomic subsites, or the mastoid cavity obligates standard canal wall up techniques. Canal wall down pro­cedures are rarely required (Richter & Lee 2009). As demonstrated in our case, the clinical presentation of CC may not be typical as that suggested by the crite­ria mentioned.

CASE REPORT

A 6-year-old boy presented to our clinic with left ear discomfort for one year with mild reduction hearing of the ipsilateral ear. He also had recurrent episodes of left sided otorrhoea two months prior to presentation. There was copious foul smelling blood stained discharge which partially resolved with ear drops. There was no vertigo, tinnitus or facial asym­metry. An otoscopic examination of the left ear revealed an intact, dull tympanic membrane and a whitish mass in the middle ear. There was posterior ear canal wall sagging with keratin debris. The tuning fork test revealed a conduc­tive hearing loss on the left. Pure tone audiogram showed moderate conductive hearing loss with an air bone gap of 40dB on the left and normal hearing on the right. Tympanometry type B was found on the left and normal on the right.  High resolution computed tomography (HRCT) of the temporal bone was performed and showed evidence of extensive choles­teatoma with erosion of the scutum and ossicles (Figure 1).

He was subjected to elective mastoid exploration and intraoperatively, there was a large attic perforation seen with overlying keratin debris. The pars tensa was intact while the postero-superior wall of the external auditory canal was eroded. The mastoid, mesotympanum and epitympanum were filled with granu­lation tissue. The ossicles including the stapes footplate were eroded and the body of the incus was enveloped by gra­nulation tissue. The tegmen tympani, round window and oval window were in­tact. There was dehiscence of the facial canal along the tympanic segment. The vertical, tympanic and labyrinthine seg­ments of the facial canal were intact and preserved. In view of the extensiveness of the disease, he underwent radical mastoidectomy and tympanoplasty type V. Postoperatively, the patient was con­tinued on intravenous rocephin and mastoid bandage for 2 days. Ribbon gauze soaked with BIPP packing was inserted and kept for 2 weeks.

At the time of writing, the patient remains well and has no more ear discharge. The left mastoid cavity was well epithelized and the neo-tympanic membrane was intact.

DISCUSSION

It is well accepted that CCbehave in a more aggressive manner than the ac­quired form. The most common present­ing complaint is hearing reduction (Dar­rouzet et al. 2002; Nelson et al 2002). As the disease progress a patient may present with vertigo, facial nerve palsy or intracranial abscess (Darrouzet et al. 2002). Early diagnosis decreases the size of CC and subsequently decreases the incidence of complications. Early de­tection is possible via routine audiological or otological screening.

There are several theories on the pa­thophysiology of congenital cholestea­toma of the middle ear include presence of congenital cell rest, metaplasia of mid­dle ear epithelium, and papillary ingrowth through an intact tympanic membrane (Bennett et al. 2006).  Research reports depict that the most common location are anterior superior quadrant followed by posterior superior quadrant of the tym­panic membrane (Darrouzet et al. 2002; Koltai et al. 2002; Bennet et al. 2006; Nelson et al. 2002). It is believed that these cholesteatomas behave in a more aggressive manner than the acquired form. This is based on frequent findings of more extensive invasion in a normally pneumatized temporal bone with ossicu­lar and labyrinthine involvement at initial surgery (Darrouzet et al. 2002).

Koltai et al. (2002) reported that most cholesteatoma start out as a matrix en­closed spherical keratin pearl in the ante­rior superior quadrant. Accordingly, the pearl then grows like a round inflated balloon. Anterior growth is towards the eustachian tube, inferiorly towards the hypotympanum and posteriorly towards the handle of the malleus. Posterior growth may extend further, involving the incudostapedial joint and the stapes su­prastructure, as well as up towards the incudomalleolar joint, around the incus, and into the attic. The growth of CCs may progress from the attic into the antrum and then into the mastoid and follows the pattern of the enlargement of other cate­gories of middle ear cholesteatomas. As there have been no case reports of CCs involving the ottic capsule, Koltai et al. (2002) concluded that a young child with otorrhoea, conductive hearing loss and tympanic membrane perforation at a nontraditional location with cholestea­toma filling the mastoid cavity, like in this patient, may represent the end point in the natural history of CC. This observa­tion supports the notion that this case should be classified as CC. In addition, the staging system proposed by Potsic et al. (2002)(Table 1) and Nelson et al. (2002)(Table 2) would categorise this case as the last stage, namely stage 4 and type 3 respectively. In the staging system proposed by Potsic et al. (2002) extension. On the other hand, type 3 in Nelson’s classification refers to CCs in mesotympanum with mastoid extension as well.

The age of this patient at presentation favours CC even though the lesion was outside the accepted definition. Findings from large series revealed that the occur­rence of CC is among younger children (mean age 5.6 years) (McGill et al. 1991; Rizer & Luxford 1998) compared to ac­quired cholesteatoma (mean 9.7 years) (Koltai et al. 2002). The presence of tym­panic membrane perforation in this pa­tient does not exclude the diagnosis of CC as this may still occur with sufficient growth of CC. This is supported by the cases reported by Koltai et al. (2002) who found that CC occurs in young child­ren (ages 3-6 years) presenting with sudden unrelenting otorrhoea, with little or no history of otitis media.

High resolution computed tomography (HRCT) of the temporal bone of these patients generally shows complete occu­pation of the mastoid by soft tissue that causes osteolysis of the mastoid septa. At exploration, tympanic membrane per­foration has been observed at various points in the drum other than the pars flaccida or the posterior quadrant. Accor­dingly, during mastoidectomy, the entire mastoid, from antrum to tip, is host to the cholesteatoma. The presence of tym­panic membrane perforation in an exten­sive CC suggests 2 possible mechan­isms. One is that the volume of choles­teatoma exceeds the capacity of the middle ear and mastoid, resulting in tym­panic membrane perforation. The other is that tympanic membrane perforation and subsequent infection accelerate the growth of the CC, resulting in complete filling of the middle ear and mastoid. Ac­quired cholesteatoma can also present with otorrhoea and complete cholestea­toma invasion of the middle ear and mastoid, but tympanic membrane perfo­ration and otorrhoea typically occur well before the entire mastoid is involved (Koltai et al. 2002). In this case report, even though the perforation is at the pars flaccida in the posterior quadrant, it is still possible that the cholesteatoma is con­genital in origin. There was no history of a chronic discharging ear or ear surgery in this patient to support that it is ac­quired.

As mentioned earlier, recently, two staging systems for CC of the middle ear have been suggested. There was a sta­tistically significant association between the stage, hearing outcomes and residual disease. In both staging systems, the more advanced the disease the higher the recurrence rate. This patient falls into stage 4 in Potsic’s and type 3 in Nelson’s classification. Therefore, this patient will require long term follow up. For the same reason radical mastoidectomy was per­formed in this patient in order to eradi­cate the cholesteatoma.

It had been almost two years from the operation and there were still no signs of recurrence seen at the time this manu­script was written.

CONCLUSION

Early detection of CCs is crucial as it may limit the size of retrotympanic cholestea­toma and reduce the possible risks and complications from surgery as well as from the disease itself.A high index of suspicion in a young child with reduced hearing and an intact tympanic mem­brane may help in the diagnosis of CCs.