Keratosis obturans and external ear canal cholesteatoma: how and why we should distinguish between these conditions

Abstract

Keratosis obturans and external ear canal cholesteatomas have been considered as separate entities for the last 20 years, after being regarded as variations of the same disease for at least 87 years. While both disorders are distinct, they do have some overlapping characteristics which may make it difficult to reach a definite diagnosis. This review explores the diagnostic dilemmas which may arise, and discusses the classification, aetiology, pathogenesis and management of these conditions. We concur that external ear canal cholesteatoma and keratosis obturans are different conditions and conclude that the presence of osteonecrosis and focal overlying epithelial loss are the most reliable features favouring the diagnosis of external ear canal cholesteatoma over keratosis obturans. Furthermore, whilst keratosis obturans can be managed successfully by regular aural toilet, external ear canal cholesteatoma may require surgical intervention depending on the extent of the disease.

Surgical results of external canal cholesteatoma

“…There were 42 operations for EACCs in this series; however, during the same period there were 11 325 inpatient operations for chronic otitis media according to the medical records of Chi Mei Medical Center. Differential diagnosis between EACC and hyperkeratosis obturans has been well discussed in the literature [12,13]. We were able to find local bony erosion and periostitis in EACC while the hyperkeratosis could cause external canal ballooning, drum thickening, and keratin plug without evidence of bony erosion.…”

Pathologie de l’oreille

“…Ces deux lésions se traduisent par une accumulation de lamelles de kératine dans le CAE [20]. Dans la kératose obturante (KO), l'accumulation de lamelles cornées est concentrique au conduit et peut s'accompagner d'un élar-gissement progressif, circonférentiel, du conduit osseux.…”

Obstruction of the external auditory canal by a keratin cast: Keratosis obturans or cholesteatoma?

“…1,2 CEAC is usually seen in older patients with chronic dull pain in one ear, a lack of hearing loss, and no associated lung or sinus abnormalities. 1,2,4 The radiographic findings of osteonecrosis or bony erosion appear to be the most reliable criteria that distinguish KO from CEAC, as CEAC usually demonstrates these radiographic abnormalities. 2 A more recent case series, however, described 3 cases of KO that also demonstrated bony erosion on CT scan.…”

“…[1][2][3] Often, there is clinical and histopathologic overlap between KO and a cholesteatoma of the external auditory canal (CEAC). [1][2][3] We report the case of a patient who presented to our dermatology clinic with a keratin cast obstructing the external auditory canal and discuss the clinical and radiographic features of the two lesions that comprise that clinical differential diagnosis.…”

“…2 KO and CEAC have traditionally been classified as variations of the same disease. However, these conditions have been classified by some as distinct entities on the basis of differences in clinical presentation and radiographic findings.…”