Cholesteatoma are cystic masses lined with stratified keratinizing squamous epithelium and most develop in the middle ear cavity.They rarely originate in the external auditory canal (EAC) with an estimated incidence of 1.2 per 1,000 of all new otologic patients (Anthony and Anthony, 1982). External auditory canal cholesteatoma (EACC) may develop spontaneously (idiopathic) or as a consequence of stenosis, inflammation, obstruction, tumor, trauma, radiation and surgery (Table 1) (Dubach et al., 2010).In the spontaneous (primary) form of EACC, disturbed local circulation of the epidermal layer of the tympanic membrane and the auditory canal was claimed to be the etiologic factor for disturbed epithelial migration in the area of the EAC (Makino and Amatsu 1986). However, thisturned out to be false according to a control study showing thatthere was no significant difference between normaland EACC in
epitheliummigration velocity (Bonding and Ravn, 2008). Thus the debate on the pathogenesis of EACC is still ongoing.
Clinically, patients with EACC present with chronicdull pain and otorrhea, which commonly is purulent (Naim, et al., 2005). The pain is caused by the invasion of the squamous tissue into the adjacent bony canal with periosteitis(Naim, et al., 2005). The patients usually do not complain of hearing loss but in some cases, they present with conductive hearing loss that is caused by occlusion of the external canal by the debris or the cholesteatoma (Naim, 2004).
Some patients are asymptomatic, especially in early staged diseases. In a meta-analysis done by Dubach, et al., the presented cardinal symptoms of EACC patients were unilateral otorrhea in most of the studies (5 of 13) and unilateral otalgia (4 of 12) or itching was also reported.
According to a case series of 34 patients with EACC reported by Dubach, et al.,
secondary EACC had random and even multifocal location,whereasidiopathic (primary) EACC cases were typically located at the floor ofthe auditory canal in majority of the studies (12 out of 12 patients and 8 out of 13 studies, respectively) (Fig. 1, Table 2) (Dubach and Häusler, 2008, Dubach, et al., 2010).The differential diagnosis of EACC includes medial canal fibrosis, malignant otitis externa, squamous cell carcinoma and which is most difficult to distinguish from EACC, keratosis obturans (Dang and Palacios, 2005). Keratosis obturans is the accumulationof large plugs of desquamated keratin in the ear canal, whereas EACC is characterized as the invasion of squamous tissue into localized areas of bony erosion of the
２ external auditory canal(Piepergerdes,et al., 1980).
EACC occasionallyextend into the middle ear cavity, mastoid,sigmoid sinus, facial nerve, temporomandibular joint and skull base. Naim,et al.classified this disease into four stages: stage I with hyperplasia of the canal epithelium, stage II including periosteitis, stage III including a defective bony canal, and stage IV showing an destruction of adjacent anatomic structure such as mastoid, skull base, sigmoid sinus, temporomandibular joint and facial nerve (Table 3, Fig. 2) (Naim,et al., 2005).
Treatment of primary EACC is controversial. Dubach and Häusler aimed to effect a curative operation in their EACC patients and considered conservative cleaning at short intervals as a second option (Dubach and Häusler, 2008). Lin reported that to prevent further occult invasion in primary EACCs, surgery is required so that the cholesteatoma and eroded bone can be excised (Lin, 2009). On the other hand, Darr and Linstrom reported that in patients with primary EACC, good control of disease can be achieved through careful, regular, in-office debridement, even in advanced cases (Darr and Linstrom, 2010). Chang,et al. introduced self-cleansing of EAC with acetic acid (dilute vinegar solution) which was effective managing primary EACC without middle ear or mastoid involvement (Chang,et al., 2012). Thus, additional research on the optimal management of EACC is required.In this present study, we performed a retrospective medical record reviewto evaluate the effectiveness of nonsurgical management in primary EACC and to determine the optimal management.
３
Table 1.Etiologic classification of external auditory canal cholesteatoma (Dubach, et al., 2010).
Category Potential risk factors for idiopathic form, cause for secondary form
Idiopathic Microangiopathy (nicotine abuse, diabetes), microtrauma (cotton tipped applicator abuse), remnants of 1st branchial cleft, epidermoid cysts….
Secondary Poststenotic Ear canal atresia, exostosis, osteoma, fibrous dysplasia, M. Paget
Postoperative Tympanoplasty, ossiculoplasty, mastoidectomy
Posttraumatic All forms of macroscopic trauma (retention of epithelium by scars, in breaches)
Posttumorous Remission of Langerhans’ cell histiocytosis after chemotherapy
Radiogenic Obliterative endarteritis, osteoradionecrosis
Postinflammatory Medial canal fibrosis, lues, scarlet fever, mycetoma, M.
Darier, measles, diphtheria Postobstructive Foreign body granuloma, verrucae
４
Fig. 1.Proportion of external auditory canal cholesteatoma (EACC)distribution(Dubach and Häusler, 2008).
(A) Idiopathic (primary) EACC with the predominance of inferior wall involvement. (B) Secondary EACC with ubiquitous distribution.
５
Table 2.Meta-analysis of 13 case series of external auditory canal cholesteatoma (Dubach, et al., 2010).
６
Table 3.Stages of external auditory canal cholesteatoma (Naim, et al., 2005).
Stage I Hyperplasia and hyperemia of the auditory meatal epithelium. Increased apoptosis rate in the upper part of the beginning cholesteatoma (Fig. 1-A) Stage II Localized inflammation of the hyperproliferated epithelium and adjacent
periosteitis. No destruction of the bony ear canal. Accumulation of the keratin debris. Clinically, dull pain and when super-infected, otorrhea is present (Fig.
1-B)
[hyperplasia with erythema (IIa),denuded not eroded bone (IIb)]
Stage III Destruction of the bony ear canal with sequestrated bone (aseptic
osteonecrosis). Excavation of the epithelium into the adjacent bony canal.
Accumulation of keratin debris with possible super-infection and otorrhea (Fig. 1-C)
Stage IV Spontaneous destruction of the adjacent anatomical structures (subclasses) with possible otorrhea, hearing loss, facial nerve palsy, sigmoid sinus thrombosis, and endocranial abscess
subclasses: mastoid, skull base with sigmoid sinus, temporomandibular joint, facial nerve
７
Fig. 2.Stages of external auditory canal cholesteatoma (EACC)(Naim, et al., 2005).
Stage I (A),II (B) and III (C) EACC.
A B
C
８