Pathogenesis of sinus cholesteatoma

Cholesteatoma in chronic otitis media secondary to pars tensa perforation

BACKGROUND

Acquired cholesteatoma secondary to pars tensa perforation was rare in clinic.

OBJECTIVES

In this study, we explored factors related to acquired cholesteatoma in chronic otitis media patients with pars tensa perforation.

MATERIAL AND METHODS

262 adults (296 ears) with pars tensa perforation were divided into four groups: anterior perforation group, posterior perforation group, central perforation group, and marginal perforation group. Analysis was carried out in terms of cholesteatoma formation, adhesion of perforation edges, mastoid pneumatization, and the function of eustachian tube.

RESULTS

Cholesteatoma was found in 34% (18 in 53 ears) in posterior perforation group, 14.3% (14 in 98 ears) in marginal perforation group, and 2.5% (2 in 80 ears) in anterior perforation group. For subjects with adhesion in perforation edges, cholesteatoma was approved in 94% of posterior perforation, 42% of marginal perforation and 25% of anterior perforation groups. The adhesion in perforation edges and function of eustachian tube instead of mastoid pneumatization were statistically significant for cholesteatoma formation.

CONCLUSIONS AND SIGNIFICANCE

Acquired cholesteatoma was mostly found in patients with posterior and marginal perforation, followed by anterior perforation. Adhesion of perforation edges was another risk factor for cholesteatoma formation. Eustachian tube also functioned by influencing the ventilation of middle ear.

Mongolian Gerbils as a Model for the Study of Cholesteatoma: Otoendoscopic as a Diagnostic Tool

Introduction  Cholesteatoma is a disease with significant clinical impact but is incompletely understood. The challenge of performing studies with long-term follow-up in humans is a factor that has restricted the advance of knowledge in this field. Thus, the use of animal models is highly pertinent, and the Mongolian gerbil model has emerged as one of the most useful.

Objective  The present study aims to evaluate, through serial otoendoscopies, the development and characteristics of pars flaccida retraction pocket and cholesteatoma in Mongolian gerbils after obliteration of the eustachian tube and compare it with the control group.

Methods  Forty Mongolian gerbils were divided into two groups of 20 animals each. In the intervention group, the animals were followed with serial otoendoscopies after eustachian tube obliteration. In the control group, the animals were only followed through serial otoendoscopies.

Results  At the end of the 16-week follow-up, cholesteatoma was present in 13 of 38 (34.2%) ears in the intervention group, and in 7 of 34 (20.6%) in the control group ( p  = 0.197). When we considered cholesteatoma and its potential precursor, pars flaccida retraction pocket, in a combined way, we verified it in 23 of 38 (60.8%) in the intervention group and in 11 of 34 (32.3%) in the control group ( p  = 0.016).

Conclusions  Over the 16 weeks of follow-up, serial otoendoscopies enabled us to evaluate the formation and development of pars flaccida retraction pockets and cholesteatomas in Mongolian gerbils and proved to be an excellent diagnostic tool.

Experimental cholesteatoma: a comparison between spontaneous and induced models

OBJECTIVE

To compare the incidence and the histopathological aspect of spontaneous and two induced Mongolian gerbils' models of cholesteatoma: External Auditory Canal (EAC) obliteration model and the Auditory Tube (AT) cauterization model.

METHODS

Fifty-four ears of 27 animals were divided into EAC obliteration, AT cauterization, and control groups and histologically assessed for cholesteatoma incidence and classification at intervals of 2, 4, 8, and 16 weeks.

RESULTS

Cholesteatoma was diagnosed in 30 of the 53 ears evaluated with a significantly higher incidence in groups that received some type of intervention (p<0.0001). It was not possible to histologically distinguish cholesteatomas of the same stage between the study groups.

CONCLUSION

Although we observed a significant increase in cholesteatoma incidence with the two methods used when compared to the control group, all developed cholesteatomas were apparently identical from a histological point of view.

Tympanic membrane perforations: a critical analysis of 1003 ears and proposal of a new classification based on pathogenesis

PURPOSE

To present a large series ears with tympanic membrane perforations (TMP), to describe their characteristics, and to propose a new classification system based on the pathogenesis of TMP.

METHODS

This cross-sectional study was conducted at a tertiary university hospital with 1003 ears (792 consecutive patients with TMP in at least 1 ear). Otoendoscopy and audiometry were performed. Perforation measurements and their locations were digitally assessed. TMP with no suggestive signs of previous retraction were classified as Group 1, and those with possible previous retraction were classified as Group 2. Signs of retraction previous to the TMP, symptom length, perforation size and location, status of the contralateral ear, and hearing status were compared.

RESULTS

Group 1 comprised 63.5% of the included ears. Compared to Group 2, Group 1 presented a higher rate of central perforations (99% vs. 53%), a shorter duration of symptoms, smaller perforations (mean area: 18.5% vs. 41.4%), a higher rate of perforations in the anterior quadrants, better hearing levels (mean tritonal gap: 23.9 dB vs. 29.2 dB), and a lower rate of abnormal contralateral ears (28% vs. 66%).

CONCLUSION

The classification of TMP into two groups based on signs of previous retractions is feasible and indicates two different levels of disease severity. While the group without previous signs of retraction comprises ears with more limited disease, membranes with previous retraction seem to show more severe disease and, consequently, a less functional middle ear.

Analysis of Inflammatory and Homeostatic Roles of Tissue-resident Macrophages in the Progression of Cholesteatoma by RNA-Seq

BACKGROUND

Tissue-resident macrophages (TRMØs) can act as innate-immune sentinels to protect body against microbe invaders and stimulating materials such as cholesterol crystals in cholesteatoma, as well as to preserve tissue integrity by cleaning unwanted cellular debris.

METHODS

TRMØs in the incised middle ear tissues were obtained from the patients with cholesteatoma as an experimental group and the patients without cholesteatoma as a control group. Differential gene expression profiling of TRMØs was conducted between two groups by analyzing GO processes, KEGG and GSEA pathways of inflammation, tissue repair and homeostasis.

RESULTS

The current study showed that 145 of 7060 genes were significantly up-regulated (logFC>2 and FDR <0.05) when compared with the patients without cholesteatoma. GO process, GSEA and Cytoscape analysis of the over-expressed genes illustrated the boosted inflammatory and anti-infection functions of TRMØs existed neutrophil function, leukocyte migration, and adaptive immune response involved receptors and signaling pathways. Whereas the homeostasis and repair functions of TRMØs were affected from up-regulated genes, such as over-expressed keratin-13 that helped form the outer keratinising squamous epithelial layer, and over-expressed MMPs that activated the extracellular matrix molecules to promote inflammation and disturb tissue remodeling. Additionally, 74 down-regulated genes (logFC<-2 and FDR <0.05) also affected the homeostasis and repair functions by affecting extracelluar matrix structure and contractile fibres in TRMØs.

CONCLUSIONS

The cellular and molecular levels in cholesteatoma is attributable to chronic infection and several disturbed cellular biological processes involving cell integrity and tissue remodeling.

Clinical Characteristics of Pars Tensa Cholesteatoma: A Comparative Study of Area-Based Classification Systems Proposed by the Japanese Otological Society and the European Academy of Otology - Neuro-Otology

OBJECTIVES

To assess the clinical characteristics of extent patterns in pars tensa cholesteatoma.

MATERIALS AND METHODS

This was a retrospective chart review. Forty-four patients with pars tensa cholesteatoma who underwent primary surgery at a tertiary academic medical center were included. The main outcomes measured were sex, age, clinical background, and stage classification of pars tensa cholesteatoma (including the extent of cholesteatoma and involvement of the sinus tympani) according to two staging classifications: criteria advocated by the Japanese Otological Society (JOS) and those advocated by the European Academy of Otology and Neuro-Otology (EAONO)/JOS joint consensus statements.

RESULTS

The mean patient age ± standard deviation was 38.4±19.6 years. The patients comprised 19 men and 25 women. According to the JOS classification, 18 ears (40.9%) were classified as stage I, 22 (50.0%) as stage II, and 4 (9.1%) as stage III. According to the EAONO/JOS joint consensus statements, 14 ears (31.8%) were classified as stage I, 26 (59.1%) as stage II, and 4 (9.1%) as stage III. Fourteen ears (31.8%) demonstrated involvement of the sinus tympani. Four ears (9.1%) that were originally categorized as stage I cholesteatoma by the JOS criteria showed sinus tympani invasion and were subsequently categorized as stage II according to the EAONO/JOS criteria.

CONCLUSION

We determined the clinical characteristics of pars tensa cholesteatoma based on the novel and well-defined classification criteria. Further studies including long-term outcomes are necessary to demonstrate the clinical relevance of the discrepancy between the two criteria with respect to involvement of the sinus tympani.

Role of Eustachian Dysfunction and Primary Sclerotic Mastoid Pneumatisation Pattern in Aetiology of Squamous Chronic Otitis Media: A Correlative Study

Squamous chronic otitis media (COM) implies formation of a retraction pocket (inactive form) or frank cholesteatoma (active form) in pars tensa or pars flaccida of tympanic membrane. A retraction pocket or frank cholesteatoma are believed to occur due to tubal dysfunction. The present study was undertaken to investigate the pattern of mastoid pneumatisation and Eustachian dysfunction by dynamic slow motion videoendoscopy (DSVE) in cases of both, active and inactive type of squamous chronic otitis media (COM). 52 patients (65 ears) comprising of twenty-six ears with pars flaccida squamous disease and 39 ears with Pars Tensa squamous disease were enrolled for the study. DSVE findings, in terms of grade and type of Eustachian dysfunction were noted. Mastoid pneumatization pattern on CT-scans, and peroperative status of mastoid pneumatisation, especially contracted mastoid with anteriorly placed sigmoid sinus or low lying dura were also recorded for every case while performing tympano-mastoidectomy. Primary sclerotic/diploic type of mastoid pneumatisation pattern and Eustachian dysfunction were found to have inverse relationship in the cases of squamous otitis media. Eustachian dysfunction, diagnosed on DSVE, had significant association with both pars flaccida (P = 0.0001) and pars tensa disease (P = 0.0007). Primary sclerotic or diploic mastoid were found to be more common in ears with pars flaccida squamous disease than pars tensa COM (46.15% vs. 38.46%, P < 0.05).

A new theory interprets the development of a retraction pocket as a natural self-healing process

PURPOSE

The thesis that cholesteatoma evolves from a retraction pocket is widely accepted today. Yet, its prime etiology, the question of what triggers the invagination of healthy skin, still remains unclear despite centuries of investigations into the origin of cholesteatoma. A new idea interprets the horizontal migration of skin into the middle ear cavities as a self-healing process, curing an underlying inflammation in the tympanic cavity, through the overgrowth and contact with immunologically active tissue.

METHODS

A retrospective analysis of the interrelation of retraction pockets and underlying granulation tissue was conducted in 209 second-look cholesteatoma surgeries over the last decade.

RESULTS

A stable tympanic membrane over aerated, healthy middle ear mucosa was found in 71.3% of cases. In 11%, small retractions with air in other parts of the middle ear cleft (epitympanic, sinus or anterior mesotympanum) were described. In 6.2%, granulations under a retraction were found. Only 3.8% of the reports revealed air behind a retraction or did not provide enough information on the mucosa situation behind the drum membrane.

CONCLUSIONS

A new hypothesis interprets the origin of a retraction pocket-the precursor of a cholesteatoma-as a natural attempt by the body to cure an underlying inflammation in a cavity. Analogous phenomena exist, e.g. the migration of the omentum towards a local inflammation in the abdomen. This idea, which is supported by the findings in our 209 second-look surgeries, is the first explanation of the origin of retraction pockets that is compatible with the various characteristics of original or recurrent cholesteatoma. A prophylaxis against a recurrent cholesteatoma might be attained by securing free drainage of the mucosa into the tubal orifice with the use of thin silicone foils in an attempt to prevent any granulation in the middle ear cleft, similar to the principles of modern rhinosinusoidal surgery with its emphasis on unblocked mucosa clearance. This allows gas production in the healed middle ear mucosa to recover, reducing the risk of a recurrent retraction.

[The peculiar clinical features of different types of acquired cholesteatoma of the middle ear]

We have undertaken the analysis of the specific clinical manifestations of acquired cholesteatoma of the middle ear in 437 chronic patients suffering from this pathology. 96.1% of them presented with primarily acquired cholesteatoma of the middle ear (including 53.3% having attic cholesteatoma, 22.8% with sinus cholesteatoma, and 19.9% of tensa retraction cholesteatoma). 3.9% of the patients exhibited a different mechanism of development of cholesteatoma. The secondary acquired mesotympanic cholesteatoma formed in association with the long-term chronic inflammation of the middle ear, concomitant perforation of the tympanic membrane and epithelial invasion from the edge of the tympanic membrane perforation and middle ear cavity. Typmanosclerosis of different degree and localization played an important role in the enhancement of the prevalence of this condition. All types of acquired cholesteatoma were found to extend beyond the point of origin of the disorder. The maximum destruction of the ossicular chain was documented in the patients presenting with sinus cholesteatoma. Those with secondary acquired cholesteatoma showed the worst functional capacity as a result of rigid fixation of the auditory ossicles. The overall cholesteatoma relapse rate (including both residual and recurrent cholesteatoma) was estimated to be 15.6%. It is concluded that the surgical strategy should be chosen on an individual basis for each concrete patient. The long-term observation of the treated patients with the application of the up-to-date radiological techniques is believed to be the indispensable prerequisite for the successful management of the complicated pathology under consideration.

The Role of Tympanic Membrane Retractions in Cholesteatoma Pathogenesis

Objective

To analyze the contralateral ear (CLE) of patients with cholesteatoma and to correlate the cholesteatoma growth pattern in the affected ear with the findings in the CLE.

Methods

Videotoscopy of both ears in 432 patients with cholesteatomas classified as posterior epitympanic (PEC), posterior mesotympanic (PMC), two routes, or undetermined. Tympanic membrane (TM) retractions were classified by location and severity and TM perforations according to signs of previous TM retraction.

Results

TM retraction was the most prevalent alteration in the CLE (42.6%). Cholesteatoma was observed in 17.4%. In patients with PEC, the retraction in the CLE was more frequent in the PF (66.7%) than in the PT (1.4%), and in those with two-route cholesteatoma, the retraction in the CLE most frequently involved both the PT and PF (65.6%; p < 0.0001).

Conclusion

Our results confirm the essential role of TM retraction at least in the earlier phases of cholesteatoma pathogenesis.

Evaluation of YAP signaling in a rat tympanic membrane under a continuous negative pressure load and in human middle ear cholesteatoma

OBJECTIVES

Mechanotransduction plays an important role in cell-proliferative activities. Negative pressure in the middle ear is thought to be an important factor related to the etiology of acquired middle ear cholesteatoma. However, the correlation between negative pressure in the middle ear and the mechanism of middle ear cholesteatoma formation remains unclear. In this study, we investigated the expression of key molecules for mechanotransduction immunohistochemically.

METHODS

An immunohistochemical analysis was performed using anti-Wnt5a (a marker of alternative Wnt signaling), -Yes-associated protein (YAP) (a marker of mechanosensing) and -pYAP (phosphorylated YAP at Ser 127: inactivated YAP) antibody in the tympanic membrane (TM) under a negative pressure load and in human middle ear cholesteatoma tissues.

RESULTS

The number of Wnt5a-positive cells had increased and YAP nuclear translocation was observed in epithelial and mesenchymal cells in the pars flaccida (PF) of the TM under a negative-pressure load and in human middle ear cholesteatoma tissues.

CONCLUSIONS

We demonstrated that negative pressure in the middle ear might possibly induce cell proliferation PF of TM in response to mechanical force (mechanotransduction) through YAP nuclear translocation mediated by alternative Wnt signaling, thus affecting human middle ear cholesteatoma formation.

Single dose intratympanic mesna application inhibits propylene glycol induced cholesteatoma formation

Objective:

Mesna (i.e. sodium 2-mercaptoethanesulfonate; C2H5NaO3S2) has been used in otological surgery such as cholesteatoma dissection and tympanic membrane lateralisation in atelectatic ears. However, this study aimed to investigate its effect on cholesteatoma formation.

Methods:

A total of 20 Wistar rats were divided into two groups of 10 animals. The right and left ears of control animals were treated with saline (saline control group; n = 10 ears) and propylene glycol plus saline (propylene glycol control group; n = 10 ears), respectively. In the mesna group, both ears were treated with propylene glycol plus mesna (n = 20 ears). On days 1, 8 and 15, the saline control group had intratympanic injections of 0.2 ml saline and the propylene glycol control and mesna groups had intratympanic injections of 0.2 ml 100 per cent propylene glycol. On day 22, the propylene glycol control group had a single intratympanic injection of 0.2 ml saline and the mesna group had a single intratympanic injection of 10 per cent mesna. Animals were killed 12 weeks after the last injection and the temporal bones were sent for histopathological evaluation.

Results:

The cholesteatoma formation rate was 88 per cent in the propylene glycol control group, but was significantly lower in the mesna group (p = 0.01). There were no significant differences in granulation tissue formation (p = 0.498), cyst formation in the bulla (p = 0.381), fibrosis (p = 0.072) and epithelial hyperplasia (p = 0.081) among experimental groups.

Conclusion:

Intratympanic propylene glycol administration is an effective method of promoting experimental cholesteatoma formation. Administration of a single dose of intratympanic mesna inhibited cholesteatoma formation in an animal model.

Histological analysis of retraction pocket pars tensa of tympanic membrane in children

AIMS

Histological and histochemical analysis of retraction pocket of pars tensa of tympanic membrane in children. Identification of morphological abnormalities in comparison with a healthy tympanic membrane as it is described in standard textbook. Identification of signs typical for cholesteatoma and support for a retraction theory of cholesteatoma formation.

STUDY DESIGN

A prospective study analysing 31 samples of retraction pockets taken during surgery.

DEPARTMENTS

University Hospital, Children's Medical Centre

METHODS

Samples of retraction pockets were processed by a standard process for light microscopy, stained by haematoxylin-eosin. Van Gieson's stain was used for differential staining of collagen, Verhoeff's stain for elastic fibre tissues, Alcian blue for acidic polysaccharides and PAS (Periodic Acid Schiff) method for basement membrane polysaccharides.

RESULTS

The following findings were observed in the samples of retraction pockets: hyperkeratosis (100%), hypervascularisations (100%), subepithelial fragmented elastic fibres (96%), myxoid changes (87%), subepithelial inflammatory infiltration (84%), rete pegs (71%), papilomatosis (71%), intraepithelial inflammatory cellularizations, (48%), intraepithelial spongiosis (16%) and parakeratosis (3%). No basement membrane continuity interruptions were observed. Thickness of retraction pocket, thickness of epidermis, occurrence of rete pegs and frequency of fragmented elastic fibres was higher in a Grade III stage RP than Grade II stage RP (according to Charachon).

CONCLUSION

Morphological abnormalities in the structure of retraction pockets in comparison with a healthy tympanic membrane were described. The changes are typical for a structure of cholesteatoma (these changes are common in matrix and perimatrix), supporting retraction theory of its origin. Our observations show that it is inflammation that probably plays a key role in the pathogenesis of retraction pocket. The frequency of some of the changes increases with the stage of retraction pocket (II-III according to Charachon). Basement membrane continuity interruptions are not typical for retraction pockets.

A new theory on the pathogenesis of acquired cholesteatoma: Mucosal traction

OBJECTIVES/HYPOTHESIS

Although the migration of its squamous outer surface of the tympanic membrane has been well characterized, there is a paucity of data available concerning the migratory behavior of its medial mucosal surface. Existing theories of primary acquired cholesteatoma pathogenesis do not adequately explain the observed characteristics of the disease. We propose a new hypothesis, based upon a conjecture that mucosal membrane interactions are the driving force in cholesteatoma.

STUDY DESIGN

A retrospective chart review and a prospective observational cohort study in rats.

METHODS

After developing the new theory, it was tested through both clinical and experimental observations. To evaluate whether impairment of middle ear mucociliary migration would influence cholesteatoma formation, a retrospective chart review evaluating cholesteatoma occurrence in a sizable population of patients with either primary ciliary dyskinesia (PCD) or cystic fibrosis (CF) was performed. To study mucosal migration on the medial aspect of the tympanic membrane, ink tattoos were monitored over time in a rat model.

RESULTS

No cholesteatomas were identified in either PCD patients (470) or in CF patients (1,910). In the rat model, mucosa of the posterior pars tensa migrated toward the posterior superior quadrant, whereas the mucosa of the anterior pars tensa migrated radially toward the annulus.

CONCLUSION

Mucosal coupling with traction generated by interaction of migrating opposing surfaces provides the first comprehensive theory that explains the observed characteristics of primary acquired cholesteatoma. The somewhat counterintuitive hypothesis that cholesteatoma is fundamentally a mucosal disease has numerous therapeutic implications.

Large-scale proteomics differentiates cholesteatoma from surrounding tissues and identifies novel proteins related to the pathogenesis

Cholesteatoma is the growth of keratinizing squamous epithelium in the middle ear. It is associated with severe complications and has a poorly understood etiopathogenesis. Here, we present the results from extensive bioinformatics analyses of the first large-scale proteomic investigation of cholesteatoma. The purpose of this study was to take an unbiased approach to identifying alterations in protein expression and in biological processes, in order to explain the characteristic phenotype of this skin-derived tumor. Five different human tissue types (cholesteatoma, neck of cholesteatoma, tympanic membrane, external auditory canal skin, and middle ear mucosa) were analyzed. More than 2,400 unique proteins were identified using nanoLC-MS/MS based proteomics (data deposited to the ProteomeXchange), and 295 proteins were found to be differentially regulated in cholesteatoma. Validation analyses were performed by SRM mass spectrometry. Proteins found to be up- or down-regulated in cholesteatoma were analyzed using Ingenuity Pathway Analysis and clustered into functional groups, for which activation state and associations to disease processes were predicted. Cholesteatoma contained high levels of pro-inflammatory S100 proteins, such as S100A7A and S100A7. Several proteases, such as ELANE, were up-regulated, whereas extracellular matrix proteins, such as COL18A1 and NID2, were under-represented. This may lead to alterations in integrity and differentiation of the tissue (as suggested by the up-regulation of KRT4 in the cholesteatoma). The presented data on the differential protein composition in cholesteatoma corroborate previous studies, highlight novel protein functionalities involved in the pathogenesis, and identify new areas for targeted research that hold therapeutic potential for the disease.

Influence of continuous negative pressure in the rat middle ear

OBJECTIVES/HYPOTHESIS

High negative pressure in the middle ear was thought to be closely related to the etiology of retraction-type cholesteatoma. Recently, it has been detected that mechanical forces are important factors in epithelial turnover and affect cytoskeletal remodeling. Continuous negative pressure in the middle ear may possibly accelerate the proliferation and differentiation of epithelial cells of the tympanic membrane.

STUDY DESIGN

Animal experimental study.

METHODS

Eleven adult male Sprague-Dawley rats were used, and continuous negative pressure was loaded by connecting a catheter from the rat's middle ear to the supply route of an implantable microinfusion pump, iPRECIO. At 7 days after implantation of the device, an otoendoscopic examination and micro-computed tomography (CT) analysis of the temporal bone were performed; the temporal bones were then collected for histological and immunohistochemical analysis. The degree of proliferation and differentiation of epithelial cells of the tympanic membrane was investigated immunohistochemically using the anti-cytokeratin-5 and anti-cytokeratin-10 antibodies.

RESULTS

Otoendoscopic examination revealed retraction of the pars flaccida in all of the ears under negative pressure. In the micro-CT analysis, soft tissue density area in the hypotympanum was observed in all ears under negative pressure. Histological analysis revealed thickened epithelium of the pars flaccida. In this region, the thickness of layers with cytokeratin-5-positive cells and cytokeratin-10-positive cells were increased.

CONCLUSIONS

Continuous negative pressure in the middle ear can lead to thickening of the epithelium of the pars flaccida, and may accelerate the proliferation and differentiation of epithelial cells.

Acquired cholesteatoma: summary of the cascade of molecular events

BACKGROUND

Cholesteatoma is considered a benign, gradually expanding and destructive epithelial lesion of the temporal bone. The pathogenesis of different classifications of cholesteatoma is marked by similar underlying cellular and molecular processes. Stepwise explanations of the histopathogenesis have been described previously. The current paper focuses on expounding the molecular events of cholesteatoma.

METHOD AND RESULTS

Cholesteatoma pathogenesis encompasses a complex network of signalling pathways during: epidermal hyperplasia, perimatrix-matrix interactions and mucosal disease. This paper presents a review of the molecular events driven by inflammatory mediators and enzymes during: cholesteatoma growth (cell proliferation and apoptosis); maintenance and deterioration (angiogenesis and hypoxia, oxidative stress and toxicity); and complications (bone erosion and hearing loss). The cascade of molecular events applicable to atelectasis and cholesteatoma that coexist with chronic otitis media and bone erosion as sequelae is summarised.

CONCLUSION

The role of lipids in this disease is relatively unexplored, but there is evidence in support of fatty acid role-players that needs confirmation. Future directions in lipid research to delineate molecular mechanisms are proposed.

Identification of novel cholesteatoma-related gene expression signatures using full-genome microarrays

Background

Cholesteatoma is a gradually expanding destructive epithelial lesion within the middle ear. It can cause extensive local tissue destruction in the temporal bone and can initially lead to the development of conductive hearing loss via ossicular erosion. As the disease progresses, sensorineural hearing loss, vertigo or facial palsy may occur. Cholesteatoma may promote the spread of infection through the tegmen of the middle ear and cause meningitis or intracranial infections with abscess formation. It must, therefore, be considered as a potentially life-threatening middle ear disease.

Methods and Findings

In this study, we investigated differentially expressed genes in human cholesteatomas in comparison to regular auditory canal skin using Whole Human Genome Microarrays containing 19,596 human genes. In addition to already described up-regulated mRNAs in cholesteatoma, such as MMP9, DEFB2 and KRT19, we identified 3558 new cholesteatoma-related transcripts. 811 genes appear to be significantly differentially up-regulated in cholesteatoma. 334 genes were down-regulated more than 2-fold. Significantly regulated genes with protein metabolism activity include matrix metalloproteinases as well as PI3, SERPINB3 and SERPINB4. Genes like SPP1, KRT6B, PRPH, SPRR1B and LAMC2 are known as genes with cell growth and/or maintenance activity. Transport activity genes and signal transduction genes are LCN2, GJB2 and CEACAM6. Three cell communication genes were identified; one CDH19 and two from the S100 family.

Conclusions

This study demonstrates that the expression profile of cholesteatoma is similar to a metastatic tumour and chronically inflamed tissue. Based on the investigated profiles we present novel protein-protein interaction and signal transduction networks, which include cholesteatoma-regulated transcripts and may be of great value for drug targeting and therapy development.

Laterality of acquired cholesteatoma and handedness

OBJECTIVE

To investigate a possible contribution of handedness to the development of unilateral acquired cholesteatoma.

PATIENTS

All patients with unilateral acquired cholesteatoma attending otorhinolaryngology clinic between August 2009 and February 2012 were asked about their handedness.

RESULTS

The study group consisted of 237 right-handed and 31 left-handed (11.8%) patients who included 158 male (59%) and 79 female subjects with an age range of 6 to 81 years (mean, 38.6 yr). There were no ambidexters in the present cohort. Overall, unilateral cholesteatoma involved 146 right (54.5%) and 122 left ears (45.5%). Ten of 31 patients (32.3%) with left hand predominance were female subjects. In the unilateral disease, the right ears were affected more frequently in patients with right-hand dominance (59.5%), and the left ears were more frequently affected in the left-handed patients (83.9%); this difference was statistically significant (p < 0.0001). The sex differences in the distribution of cholesteatoma side and handedness were not statistically significant (p = 0.098).

CONCLUSION

The strong relationship has been observed between the patient's handedness, and laterality of the unilateral acquired cholesteatoma may have contribution in the multifactorial process of cholesteatoma formation.

[Principles of cholesteatoma surgery]

As a potentially life-threatening disease, cholesteatoma of the petrous bone generally requires a surgical approach. Surgery aims to produce an ear that is easy to care for and is free of recurrent or residual cholesteatoma. Hearing improvement is of secondary importance. Nevertheless the sound conduction system is generally reconstructed as a single-stage procedure. There are various possible methods of dealing with a cholesteatoma: (i) preserving or reconstructing the posterior meatal wall with an aerated mastoid (closed technique) or obliteration of the mastoid completely or partially after removal of the posterior wall (closed technique); and (ii) leaving the cavity open for inspection (open technique). In our opinion any technique where the mastoid is not open for inspection should be called a closed technique. Both techniques have their specific advantages and disadvantages.

Histological and immunohistochemical study of pars tensa retraction pocket

OBJECTIVE

To study the histological and proliferation characteristics of the pars tensa retraction pocket. To investigate the hypothesis that such retraction pockets may demonstrate breaks in the epithelial basement membrane.

STUDY DESIGN

Prospective evaluation. Fifty stage II-IV surgically resected retraction pockets.

SETTING

Tertiary care academic hospital.

METHODS

Paraffin sections stained with hematoxylin and eosin. Basement membrane evaluation by Periodic acid-Schiff (PAS) and silver-methenamine (SM). Evaluation of cellular proliferation by immunohistochemistry (MIB-1 score).

RESULTS

Following are findings noted as frequent but not invariable in pars tensa retraction pockets: (1) subepithelial chronic inflammation (86%), (2) proliferation and hyperkeratinization of the outer epithelial layer, (3) epithelial cones with proliferating cells (increased MIB-1 score) in the basal epithelial layer (39%), (4) loss of the middle double collagen layer (71%), and (5) loss of the inner mucosal layer (33%). Inflammation and cellular proliferation were noted as ubiquitous among all grades. A trend was noted along progressive grades of retraction (II-IV) for an increasing incidence of basal epithelial cones, middle collagen layer loss, and inner mucosal layer loss. Focal loss of basement membrane was noted in several cases with PAS staining, but further staining with the SM in all such cases indicated the basement membrane to be intact.

CONCLUSION

A continuum of progressive histological features akin to cholesteatoma is noted with increasing grades of retraction (II-IV). Breach of the basement membrane was recently reported as a feature of cholesteatoma but is not a feature of retraction. The near universal presence of inflammation as noted suggests an etiological role.

Animal models of middle ear cholesteatoma

Middle ear acquired cholesteatoma is a pathological condition associated with otitis media, which may be associated with temporal bone resorption, otorrhea and hearing loss, and occasionally various other complications. Cholesteatoma is characterized by the enhanced proliferation of epithelial cells with aberrant morphologic characteristics. Unfortunately, our understanding of the mechanism underlying its pathogenesis is limited. To investigate its pathogenesis, different animal models have been used. This paper provides a brief overview of the current status of research in the field of pathogenesis of middle ear acquired cholesteatoma, four types of animal models previously reported on, up-to-date cholesteatoma research using these animal models, our current studies of the local hybrid ear model, and the future prospect of new animal models of middle ear cholesteatoma.

Three-Dimensional Image Analysis of the Temporal Bone in Patients with Unilateral Attic Cholesteatoma

We determined temporal bone anatomy in patients with unilateral attic cholesteatoma. We compared the affected and normal ears of ten patients with unilateral attic cholesteatoma using three-dimensionally reconstructed high-resolution computed tomography images of the temporal bone. We determined the eustachian tube angle, eustachian tube length, sizes of the tympanic orifice of the eustachian tube, the pars flaccida, and the mastoid cavity, and distances of the pars flaccida and the tympanic orifice of the eustachian tube from the epitympanic roof. No significant differences were found between the normal and affected ears with regard to the size of the eustachian tube orifice, eustachian tube length or distances of the pars flaccida and the tympanic orifice of the eustachian tube from the epitympanic roof. By contrast, the mastoid cavity and the eustachian tube angle were significantly larger in the normal ears than in the affected ears [mean, 6.99 cm3 (S.D., 4.9 cm3) vs. 1.28 cm3 (0.81 cm3) and 16.7° (4.12°) vs. 13.89° (5.30°), respectively]. The pars flaccida was significantly smaller in the normal ears [1.07 cm (0.31 cm)] than in the affected ears [2.19 cm (0.77 cm)]. The inherent anatomy of the eustachian tube may be particularly important in the formation of attic cholesteatomas.

Acquired cholesteatoma pathogenesis: stepwise explanations

BACKGROUND

Since Virchow's first, 1855 publication on cholesteatoma, this disease has been the subject of extensive debate. The pathogenesis of acquired cholesteatoma is repeatedly explained on the premises of the migration, hyperplasia and metaplasia theories, but proof for the latter theory remains limited. In retrospect, there is progress toward better understanding of all the pathological mechanisms involved, as expounded in this review.

DISCUSSION

The triggers for cholesteatoma onset are diverse, and may involve tympanic membrane trauma (i.e. perforation, displacement, retraction or invagination), tympanic membrane disease, and/or tympanic cavity mucosa disease. Research has revealed that cell migration is replaced under inflammatory conditions by hyperplasia, which triggers the onset of cholesteatoma. Lately, the hyperplasia theory gained prominence and circumscription of the papillary cone formation concept provided insight into cholesteatoma progression (growth and expansion). Diseased mucosa can contribute to the development of retraction pockets and cholesteatoma. The type of cholesteatoma trigger and the role of chronic inflammation during disease progression and recurrence are important in guiding clinical intervention.