Epithelial migration in keratosis obturans

External Ear Disease: Keratinaceous Lesions of the External Auditory Canal

Keratosis obturans (KO) and external auditory canal cholesteatoma (EACC) are two distinct keratinaceous lesions of the external ear. This article reviews the signs, symptoms, pathophysiology, workup, and treatment of each. Patients with either pathology can often be managed in the clinic with debridement; however, EACC is more likely to involve osteonecrosis and require more extensive operative management if disease is not confined to the canal on account of the bony erosion characteristic of cholesteatoma. If required for extensive disease, surgical approaches to both pathologies are similar.

Keratosis obturans: A rare cause of facial nerve palsy

Keratosis obturans, caused by the deposition of desquamated keratin plug in the external auditory canal can present with facial palsy. Young patients presenting with facial palsy, earache, and gradual hearing loss should be suspected for Keratosis obturans.

Contemporary management of keratosis obturans: a systematic review

OBJECTIVE

This study aimed to examine the medical literature regarding the natural history and management of keratosis obturans.

METHOD

PubMed was queried via the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol, and the methodological quality of each study was assessed using the Methodological Index for Non-Randomized Studies criteria.

RESULTS

Fifty-one studies were abstracted, and dual investigator screening resulted in five retrospective studies for final analysis. All studies included patients afflicted with either unilateral (n = 75) or bilateral keratosis obturans (n = 8). The definition of keratosis obturans was present in three studies: a desquamated keratin plug within the external auditory canal. Mean and median Methodological Index for Non-Randomized Studies scores were 9.5 and 9.5, respectively. All patients underwent keratosis obturans exenteration with microscopy. Two studies reported an outcome instrument to evaluate endpoints: marked stillette and audiometry. No complications were observed with follow-up periods from 3 weeks to 3.5 years.

CONCLUSION

This comprehensive review highlights a lack of published evidence relating to keratosis obturans. However, it appears keratosis obturans treatment is safe and efficacious with identifiable clinical practice patterns.

A Novel Topical Treatment for Keratosis Obturans

OBJECTIVE

To present and evaluate the treatment of keratosis obturans (KO) using miconazole/triamcinolone 0.1% crème gauzes.

STUDY DESIGN

A retrospective clinical capsule report.

PATIENTS

Twelve patients diagnosed with KO between January 2000 and July 2020 visiting our tertiary hospital setting, were retrospectively reviewed.

INTERVENTIONS

Either miconazole/triamcinolone 0.1% crème gauzes or periodic microscopic removal of the keratin plug.

MAIN OUTCOME MEASURES

No evidence of disease during microscopic inspection of the ear canal.

RESULTS

Successful treatment with miconazole/triamcinolone 0.1% gauzes was seen in 4/7 patients (57%) and successful treatment of periodic cleaning of the ear canal was seen in 1/5 patients (20%).

CONCLUSIONS

Topical treatment of KO with miconazole/triamcinolone 0.1% crème gauzes in the ear canal could be considered as a treatment option for patients diagnosed with KO.

Anatomy and Development of the Mammalian External Auditory Canal: Implications for Understanding Canal Disease and Deformity

The mammalian ear is made up of three parts (the outer, middle, and inner ear), which work together to transmit sound waves into neuronal signals perceived by our auditory cortex as sound. This review focuses on the often-neglected outer ear, specifically the external auditory meatus (EAM), or ear canal. Within our complex hearing pathway, the ear canal is responsible for funneling sound waves toward the tympanic membrane (ear drum) and into the middle ear, and as such is a physical link between the tympanic membrane and the outside world. Unique anatomical adaptations, such as its migrating epithelium and cerumen glands, equip the ear canal for its function as both a conduit and a cul-de-sac. Defects in development, or later blockages in the canal, lead to congenital or acquired conductive hearing loss. Recent studies have built on decades-old knowledge of ear canal development and suggest a novel multi-stage, complex and integrated system of development, helping to explain the mechanisms underlying congenital canal atresia and stenosis. Here we review our current understanding of ear canal development; how this biological lumen is made; what determines its location; and how its structure is maintained throughout life. Together this knowledge allows clinical questions to be approached from a developmental biology perspective.

A Hierarchy of Proliferative and Migratory Keratinocytes Maintains the Tympanic Membrane

The tympanic membrane (TM) is critical for hearing and requires continuous clearing of cellular debris, but little is known about homeostatic mechanisms in the TM epidermis. Using single-cell RNA sequencing, lineage tracing, whole-organ explant, and live-cell imaging, we show that homeostatic TM epidermis is distinct from other epidermal sites and has discrete proliferative zones with a three-dimensional hierarchy of multiple keratinocyte populations. TM stem cells reside in a discrete location of the superior TM and generate long-lived clones and committed progenitors (CPs). CP clones exhibit lateral migration, and their proliferative capacity is supported by Pdgfra+ fibroblasts, generating migratory but non-proliferative progeny. Single-cell sequencing of the human TM revealed similar cell types and transcriptional programming. Thus, during homeostasis, TM keratinocytes transit through a proliferative CP state and exhibit directional lateral migration. This work forms a foundation for understanding TM disorders and modeling keratinocyte biology.

Surgical management of external auditory canal lesions

Background:

Lesions arising in the external auditory canal that require surgical excision are uncommon. They are associated with a range of pathologies, including bony abnormalities, infections, benign and malignant neoplasms, and epithelial disorders.

Methods:

This paper describes a 10-year personal case series of external auditory canal lesions with chart, imaging and histopathology review.

Results:

In total, 48 lesions required surgical management, consisting of: 13 bony lesions; 14 infective lesions; 14 neoplasms with 11 histological types (including ceruminous adenoma and the extremely rare cavernous haemangioma); 3 epithelial abnormalities; and 4 other benign lesions. The surgical management is described.

Conclusion:

This study emphasises the diagnostic differences between exostoses and osteomas, and between external auditory canal cholesteatoma and keratosis obturans. It also discusses the management of aural polyps, and highlights the need to excise external auditory canal masses for histology in order to guide subsequent treatment.

External auditory canal cholesteatoma and keratosis obturans: the role of imaging in preventing facial nerve injury

We conducted a retrospective study to compare the clinical characteristics of external auditory canal cholesteatoma (EACC) with those of a similar entity, keratosis obturans (KO). We also sought to identify those aspects of each disease that may lead to complications. We identified 6 patients in each group. Imaging studies were reviewed for evidence of bony erosion and the proximity of disease to vital structures. All 6 patients in the EACC group had their diagnosis confirmed by computed tomography (CT), which demonstrated widening of the bony external auditory canal; 4 of these patients had critical erosion of bone adjacent to the facial nerve. Of the 6 patients with KO, only 2 had undergone CT, and neither exhibited any significant bony erosion or expansion; 1 of them developed osteomyelitis of the temporal bone and adjacent temporomandibular joint. Another patient manifested KO as part of a dermatophytid reaction. The essential component of treatment in all cases of EACC was microscopic debridement of the ear canal. We conclude that EACC may produce significant erosion of bone with exposure of vital structures, including the facial nerve. Because of the clinical similarity of EACC to KO, misdiagnosis is possible. Temporal bone imaging should be obtained prior to attempts at debridement of suspected EACC. Increased awareness of these uncommon conditions is warranted to prompt appropriate investigation and prevent iatrogenic complications such as facial nerve injury.

[Keratosis obturans of the external auditory canal]

Keratosis obturans is a rare condition of the bony part of external ear canal cased by hyperkeratosis of epiderm and disorders of migration process. Hyper-cumulation of desquamated epiderm in the external ear canal leads to hearing loss, earache and inflammation of ear canal skin. We present 2 cases of keratosis obturans as examples of epiderm migration disorders and difficulties in diagnosis and treatment of this disease. Keratosis obturans was diagnosed in both cases in histopathological and immunohistochemical examinations. Histopathological and molecular structure of keratosis obturans was discussed. In presented cases surgical, anti-inflammatory and keratinolytic treatment was applyied.

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

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.