[Potentially malignant disorders of the oral mucosa]

Potentially malignant disorders of the oral mucosa. The term "precancerous" is now abandoned in favor to « potentially malignant disorder » which provide a better view of the evolution a far from systematic. Of these disorders, leukoplakia is the most common while erythroplakia is rare. Their diagnoses are still defined by exclusion of other known white or red lesions. Despite progress in molecular biology, there is no marker enabling to predict malignant transformation. When feasible, excision of these lesions is recommended, irrespective of the presence or the absence of dysplasia, a pure histologic notion. It is unknown if such removal can really prevent the development of a squamous cell carcinoma. The risk of malignant transformation of oral lichen planus, lower than in leukoplakia, is better known. There is no therapeutic enabling to prevent such event. Other potentially malignant disorders such as oral submucous fibrosis, actinic cheilitis, lupus and immunodeficiency conditions are rare.

Characteristics and trends of oral leukoplakia research: A bibliometric study of the 100 most cited articles

BACKGROUND

Bibliometric analysis highlights the key topics and studies which have shaped the understanding and management of a disease of interest. Here the top-cited articles on oral leukoplakia (OL) were characterized, and research patterns and trends were analyzed.

METHODS

A comprehensive search was performed and identified in the Scopus database up to 22 February 2019 for the 100 most-cited articles on OL.

RESULTS

The number of citations of the 100 selected articles varied from 116 to 1418, with a mean of 226.7 citations per article. Both Journal of Oral Pathology and Medicine and Oral Surgery Oral Medicine Oral Pathology Oral Radiology were journals with the most articles published (n = 10). Both Hong W.K. and Lippman S. were the most frequently contributing authors (n = 9). United States (n = 43) and M.D. Anderson Cancer Center (n = 12) was most contributing country and institution, respectively. Systematic reviews/meta-analysis (n = 3) and randomized controlled trial (n = 7) were study designs with high evidence level. It is noteworthy that the majority of high-quality articles were the research of chemopreventive drugs (n = 21) and molecular markers/targets (n = 10), which may indicate a trend of key topics.

CONCLUSIONS

The results of this first citation analysis of the most-cited articles on OL provide a historical perspective on scientific evolution, and suggest further research trends and clinical practice in the field of OL.

Insight on the relationship of ABO blood grouping associated with oral premalignant lesions, conditions and inherited oral cancer syndromes

BACKGROUND

Risk factors such as chronic use of tobacco, smoking and alcohol consumption of individual's lifestyle may possibly influence the significant role in the etiopathogenesis of precancerous lesions (PL) and Conditions (PC) and lead to oral cancer. Previous studies have revealed that genetic factors have contributed to a remarkable extent in the development of this chronic disease. Limited studies have confirmed that ABO blood groups remain reportedly possible genetic factor to the specific disease such as oral malignant. In this context, we have reported that individuals in a particular blood group are more prone to develop lesions and certain types of cancer. This has thrown a light to take up an effort to conduct this present study.

MATERIALS AND METHODS

The present study covering 105 patients and grouped into three subjects with 35 participants in each. a) oral squamous cell carcinoma b) oral leukoplakia and c) submucous fibrosis. Gender and age group impact was also made to understand the interaction between the focused sample groups. A separate control was gathered from a same geographical population composed of gender-matched healthy volunteers. Slide agglutination was employed for blood grouping and results were tabulated for statistical analysis.

RESULTS

Blood group "A" exhibited a significant relationship between oral squamous cell carcinoma patient and odd ratio shown 1.74 times higher risk of developing oral cancer. Gender different and habit stimulation have increased the risk. A significant relationship was observed between ABO blood group and oral leukoplakia and oral submucous fibrosis.

CONCLUSION

Study inferred that blood group "A" is found to be at the high risk in developing oral malignant syndrome due to its susceptibility, whereas oral pre-cancer is hypothesized that individual habits are the host risk factor and transformed to carcinoma by interacting genetic factors to act upon ABO blood group.

Oral health consequences of smokeless tobacco use

Smokeless tobacco (SLT) use has many oral effects including oral cancer, leukoplakia and erythroplakia, oral submucous fibrosis (if mixed with areca nut), loss of periodontal support (recession) and staining of teeth and composite restorations. This review was aimed to provide information to identify oral lesions that occur due to the use of smokeless tobacco so that effective interventions can be undertaken to reduce morbidity and mortality from the use of SLT.

Prevalence of oral cancer, oral potentially malignant disorders and other oral mucosal lesions in Cambodia

OBJECTIVES

To obtain data on the prevalence of oral mucosal lesions (OMLs) among Cambodians, and to assess the relationship between known risk habits of oral diseases with prevalence of oral potentially malignant disorders (OPMDs).

DESIGN

This was a population-based, cross-sectional study whereby subjects were adults aged 18 years old and above. A workshop on the identification of OML was held to train and calibrate dental officers prior to data collection in the field. Sociodemographic and risk habits data were collected via face-to-face interview, whilst presence of OML and clinical details of lesions such as type and site were collected following clinical oral examination by the examiners. Data analysis was carried out using the Statistical Package for Social Science (SPSS) version 12.0. The association between risk habits and risk of OPMD was explored using logistic regression analysis.

RESULTS

A total of 1634 subjects were recruited. Prevalence of OML for this population was 54.1%. Linea alba was the most common lesion seen (28.7%). This study showed an overall OPMD prevalence of 5.6%. The most common type of OPMD was leukoplakia (64.8%), followed by lichen planus (30.8%). Subjects who only smoked were found to have an increased risk for OPMD of almost four-fold (RR 3.74, 95%CI 1.89-7.41). The highest risk was found for betel quid chewers, where the increased risk observed was more than six times (RR 6.75, 95%CI 3.32-13.72). Alcohol consumption on its own did not seem to confer an increased risk for OPMD, however when practiced concurrently with smoking, a significant risk of more than five times was noted (RR 5.69 95%CI 3.14-10.29).

CONCLUSION

The prevalence of OML was 54.1%, with linea alba being the most commonly occurring lesion. Smoking, alcohol consumption and betel quid chewing were found to be associated with the prevalence of OPMD, which was 5.6%.

Limited evidence for interventions to treat oral leukoplakia

Data sourcesCochrane Oral Health's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline Ovid, Embase, Ovid, CancerLit via PubMed. MetaRegister of Controlled Trials, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform were searched for ongoing trials.The reference lists of included studies and existing reviews were manually searched.Study selectionRandomised control trials (RCTs) including patients diagnosed with oral leukoplakia comparing any treatment to placebo or no treatment were included with no restrictions on language or date of publication.Data extraction and synthesisTwo reviewers independently checked for inclusion, performed data extraction using a specially designed form, and assessed the risk of bias for each study and by domain over all studies. The primary outcome considered was onset of oral cancer reported as dichotomous data. Secondary outcomes were clinical resolution, histological changes and adverse events that were mostly reported as ordinal data.ResultsFourteen studies with 909 participants were included in the review. Of the included studies, four compared topical interventions to placebo, nine compared systemic interventions to placebo, and one compared a combination of topical and systemic treatments versus placebo. The risk of bias was considered to be low in one study, unclear in seven, and high for the remaining six. Only three studies provided usable data on the primary outcome: cancer incidence. Clinical improvement was achieved in three studies using: systemic vitamin A or retinoids (two studies) and systemic beta-carotene or carotenoids (one study). Only two studies using beta-carotene or carotenoids were meta-analysed, showing no benefit on the outcome cancer development.ConclusionsThere is no evidence that any of the active treatments included work better than placebo in reducing the risk of developing oral cancer.

Oral precursor lesions and malignant transformation--who, where, what, and when?

Oral potentially malignant disorders (PMD) are recognisable mucosal conditions that have an unpredictable risk of transformation to squamous cell carcinoma (SCC), a lethal and deforming disease of rising incidence. Contemporary management is based on clinical recognition of suspicious lesions and incisional biopsy to enable histopathological assessment and grading of dysplasia, together with excision of high-risk lesions and long-term surveillance. However, it is impossible to predict clinical outcome or risk of malignant transformation. Our aim was to evaluate the relevance of previously identified oral precursor lesions for the development of SCC and staging of disease. We therefore retrospectively reviewed 1248 cases of SCC diagnosed in oral and maxillofacial surgery units at Newcastle upon Tyne and Sunderland hospitals between 1996 and 2009. Of them, 58 identifiable precursor lesions became malignant but only 25 had been dysplastic on initial biopsy; 19 of 33 non-dysplastic lesions exhibited lichenoid inflammation only. SCC arose most often on the ventrolateral tongue and floor of the mouth, with a mean transformation time of 29.2 months. Transformation time was significantly shorter in men (p=0.018) and those over 70 years of age (p=0.010). Patients who consumed more than 21 units of alcohol/week and those who had had interventional laser surgery to treat precursor lesions, had higher-staged tumours (p=0.048). Although retrospective, this study shows that the results of incisional biopsy and grading of dysplasia have limited use as predictive tools, and supports the view that cancer may arise in the absence of recognisable epithelial dysplasia. Our findings confirm the importance of clinical vigilance and active surveillance in the management of all patients with clinically suspicious oral lesions, irrespective of the histological findings.

[Expression of Ki-67 and P53 protein in oral squamous cell carcinoma and its clinical significance]

PURPOSE

To investigate the clinical and pathological features and its relationship with the expression of Ki-67 and p53 protein in oral squamous cell carcinoma.

METHODS

Immunohistochemical SP staining method was used to quantify the protein expression levels of Ki-67 and p53 protein in 10 cases of normal oral mucosa, 16 cases of oral leukoplakia (OLK) tissue, and 48 cases of oral squamous cell carcinoma. The relationship of the expression of Ki-67 and p53 protein to clinical and pathological data was analyzed, and SPSS17.0 software package was used for statistical analysis.

RESULTS

The positive expression rate of Ki-67 protein in normal oral mucosa, oral leukoplakia and oral squamous cell carcinoma was 30%, 56.3% and 79.2%, respectively; The positive expression rate of p53 was 0%, 43.8%, and 70.8%, respectively; Ki-67 and p53 expression had significant difference among normal oral mucosa, oral leukoplakia and oral squamous cell carcinoma (P<0.05); The expression of Ki-67 protein was significantly elevated with tumor stage, differentiation and cervical lymph node metastasis (P<0.05); The expression of p53 protein was significantly related to the degree of tumor differentiation (P<0.05); The expression of Ki-67 and p53 was positively correlated in oral squamous cell carcinoma (P<0.05).

CONCLUSIONS

The high expression of Ki-67 and p53 protein in oral squamous cell carcinoma tissues may play an important role in the development of oral squamous cell carcinoma.

[A retrospective analysis on the malignant transformation rate, time and risk factors of oral leukoplakia]

PURPOSE

A retrospective analysis was made on the oral leukoplakia (OLK) patients archived from 1978 to 2009 at the Department of Oral Medicine, Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University, to analyze the malignant transformation of oral leukoplakia and its influential factors.

METHODS

The data was studied with the SAS6.12 software package, using the methods of survival analysis and Cox regression to acquire malignant transformation rate (MTR) and malignant transformation time (MTT).

RESULTS

According to the archived files, there were 576 cases of OLK with 350 males and 226 females. Among them, 66 cases (33 males and 33 females) developed OSCC, the total MTR was 11.46%. Two hundred and sixty-seven cases were suitable for survival analysis and Cox regression. The 1-year MTR was (0.40 ± 0.40)%, (0.86 ± 0.61)% (life-table method/product-limit method); the 2-year MTR went up to (2.84 ± 1.15)%, (2.93 ± 1.18)% and the 5-year MTR was as high as (11.28 ± 2.70)%, (11.31 ± 2.71)%. In Cox regression model, location of lesion and age were the main factors that affected OLK's transformation to OSCC.

CONCLUSIONS

The MTR of OLK is related to the follow-up time; The lesion site and age are the most important risk factors. Supported by Research Fund of Science and Technology Commission of Shanghai Municipality (08DZ2271100), Shanghai Leading Academic Discipline Project (S30260) and Research Fund of Shanghai Municipal Education Commission (JDY-07061).

[Expression and its relationship of murine double minute 2 and P53 protein in oral leukoplakia and squamous cell carcinoma]

OBJECTIVE

To study the expression and its relationship of murine double minute 2 (MDM2), P53 protein in oral leukoplakia and squamous cell carcinoma.

METHODS

Immunohistochemical assay was used to detect the expression of MDM2 and P53 proteins in 15 normal oral epithelium tissues, 24 cases of oral leukoplakias and 41 cases of oral squamous cell carcinomas.

RESULTS

There were no positive expression of MDM2 and P53 in normal mucosa. With significantly difference compared with the normal group (P < 0.05), the positive rates of MDM2 and P53 were 58.3%, 75.6% and 37.5%, 68.3% in oral leukoplakia and squamous cell carcinoma. MDM2-positive rate had no significant difference (P > 0.05), while P53-positive rate was significant difference (P < 0.05) compared with oral leukoplakia and oral squamous cell carcinoma. Two kinds of indicators for further correlation analysis showed that MDM2 and P53 protein showed a positive correlation relationship both in oral leukoplakia (P = 0.018) and oral squamous cell carcinoma (P = 0.000).

CONCLUSION

The expression of MDM2 in oral leukoplakia and oral squamous cell carcinoma suggests that this gene may play a significant role in the process of carcinogenesis of oral squamous cell carcinoma. The correlation of MDM2 and P53 expression indicates that both of them may play a synergistic role in the process of carcinogenesis of oral squamous cell carcinoma.

[Application of Cochrane systematic reviews in diagnosis and treatment for oral mucosal diseases]

OBJECTIVE

To collect evidence in diagnosis and treatment of oral mucosal diseases.

METHODS

The Cochrane library (Issue 3, 2009) was searched to get the full texts of published related Cochrane systematic reviews. The results were summarized for recommendation to dentists. The current status of evidence based medicine in this field was analyzed.

RESULTS

Reliable evidence for management of oral submucous fibrosis is still limited; amifostine, hydrolytic enzymes, ice chips and Chinese medicine may be effective in preventing oral mucositis for patients with cancer receiving radiotherapy or chemotherapy; the evidence in treating oral mucositis with allopurinol mouthwash, granulocyte macrophage-colony stimulating factor, immunoglobulin or human placentral extract for patients with cancer receiving treatment is weak and unreliable yet; there is evidence that acyclovir is efficacious in prevention and treatment of herpes simplex virus infections in patients being treated for cancer; there is strong evidence that drugs absorbed or partially absorbed from the gastrointestinal tract prevent oral candidiasis in patients receiving treatment for cancer; relapses and adverse effects are common in using beta carotene, lycopene, vitamin A or retinoids to treat oral leukoplakia; only some weak evidence is provided in using cyclosporines, retinoids, steroids or phototherapy for treating oral lichen planus; the evidence about acyclovir for treating primary herpetic gingivostomatitis is insufficient; there is little research evidence for treatment of burning mouth syndrome.

CONCLUSION

It is essential to raise the quality of design and conduction of clinical trials in the field of oral mucosal disease to provide solid bases for systematic review, so that to improve evidence based treatment of these diseases.

Diagnostic evaluation and management of hoarseness

Hoarseness is a common symptom that can result from a wide spectrum of underlying causes ranging from the common cold to a malignancy. A framework for diagnostic evaluation is presented based on categorizing the myriad of causes by how they interfere with the voice production mechanism. Triaging of cases by necessity or urgency of laryngoscopy is assisted by forming a global index of suspicion based on targeted history taking. Laryngoscopy is required in most cases to obtain a diagnosis for the hoarseness. Treatments commonly prescribed for hoarseness are critically examined in this article. To listen to audio clips of patients with different types of hoarseness, please visit our website, www.medical.theclinics.com.

[Near infrared Raman spectral character and diagnostic value of squamous cell carcinoma of oral mucosa]

OBJECTIVE

To evaluate the value of the near infrared Raman spectroscope in diagnosing oral squamous cell carcinoma (OSCC).

METHODS

Near infrared Raman spectra of ten normal mucosa, twenty OSCC and thirty oral leukoplakia (OLK) cases were collected in the research. Based on the previous researches, the information of the subtracted spectra of compared group was gained by the characteristic band in them. A Gaussian radial basis function support vector machine was used to classify spectra and establish the diagnostic models. The efficacy and validity of the algorithm were evaluated.

RESULTS

By analyzing the subtracted mean spectra, the increasing peak intensity in wavenumber range of 500-2 200 cm(-1) hinted us of the high contents of DNA, protein and lipid in OSCC, which elucidate the high proliferative activity. The increasing peak intensity in the wavenumber range of 500-2 200 cm(-1) hinted us of the high contents of DNA, protein and lipid in OSCC, which elucidate the high proliferative activity, but the difference between OLK and OSCC was not as much as that between normal and OSCC. The Gaussian radial basis function support vector machine showed powerful ability in grouping and modeling of normal and OSCC, and the specificity, sensitivity and accuracy were 100%, 97.44% and 98.81% correspondingly. The algorithm showed good ability in grouping and modeling of OLK and OSCC, the specificity, sensitivity and accuracy were 95.00%, 86.36% and 96.30%.

CONCLUSION

Combined with support vector machines, near infrared Raman spectroscopy could detect the biochemical variations in oral normal, OLK and OSCC, and establish diagnostic model accurately.

[Expression of Notch1 and epidermal growth factor receptor in human tongue squamous cell carcinoma and precancerous lesion]

OBJECTIVE

To investigate the expression of Notch1 in human tongue squamous carcinoma (TSCC) and precancerous lesion, and to explore the potential relation between Notch1 and epidermal growth factor receptor (EGFR).

METHODS

The expression of Notch1 and EGFR was detected in human TSCC (n = 41), tongue leukoplakia (LP) (n = 39) and normal tongue mucosa (n = 7) by immunohistochemistry.

RESULTS

In normal tongue mucosa and LP, the positive staining of Notch1 was mainly distributed in stratum corneum, partially in stratum granulosum and stratum spinosum, but not in stratum basale, while the positive staining of EGFR was mainly distributed in stratum basale, rarely in stratum spinosum, but not in stratum granulosum and stratum corneum. In TSCC, Notch1 expression was mainly distributed in locations of squamous metaplasia, but not in peripheral cells of carcinomas, while EGFR expression was detected mainly in peripheral cells of carcinomas, but not in locations of squamous metaplasia.

CONCLUSION

Notch1 promotes the differentiation of epithelial cells in tongue mucosa and acts as a tumor suppressor in TSCC. EGFR may act as a negative regulator of Notch1 expression in epithelium of tongue mucosa and TSCC, for maintaining cell proliferation and promoting the tumorigenesis and progression of TSCC.

[Biologic analysis of recombinant human adenovirus-p53 injection in patients with oral leukoplakia ]

OBJECTIVE

Advances in tumor biology and clinical trials indicate that p53 transfer is an alternative therapy for head and neck squamous cell carcinoma. The aim of this study is to evaluate the biologic activity of multiple intraepithelial injections of Ad-p53 in patients with dysplastic oral leukoplakia, which is the most common premalignant lesion of the oral squamous cell carcinoma.

METHODS

From 2006 to 2007, 18 Chinese patients clinically and histopathologically diagnosed as dysplastic oral leukoplakia were recruited for this study. On a 15-day cycle, intraepithelial injections of Ad-p53 were administered once every three days at dose levels dependent upon lesion size/dose escalation sequence (1 x 10(8) vp). 24-48 h after the last injection, incisional biopsy were performed, and immunohistochemistry was used to examine the protein expression of P53 and P21(CIP/WAF).

RESULTS

In the postreatment patients, P53 protein and P21(CIP/WAF) protein expression were significantly enhanced (100%, 89.9%, respectively) and statistical analysis revealed the expression of P53 protein had a positive correlation with that of P21(CIP/WAF) protein (r=0.598, P<0.01).

CONCLUSION

Intraepithelial injections of gendicine is biologically active in patients with dysplastic oral leukoplakia. It may be a promising treatment for oral leukoplakia.

[Role of ataxia telangiectasis mutated in the oncogenesis of oral squamous cell carcinoma]

OBJECTIVE

To investigate the role of ataxia telangiectasis mutated (ATM) gene in the oncogenesis and progression of oral squamous cell carcinoma (OSCC).

METHODS

A total of 61 formalin-fixed and paraffin-embedded samples were obtained from patients with hyperkeratosis, oral leukoplakia, OSCC and normal healthy controls. The expression of ATM protein in all of the samples was investigated by streptavidin-peroxidase immunohistochemistry assay. PCR was also performed to detect the loss of heterozygosity (LOH) in D11s2179 of ATM gene. The correlations between ATM and the clinical and histopathological characteristics were also investigated.

RESULTS

The results indicated that the ATM expression was increased in oral premalignant lesions (P<0.05). For OSCC, 68.8% samples showed normal or increased ATM expression, while 31.3% had decreased or absent ATM expression. Significant differences were found between the group of decreased or absent ATM expression and that of normal or increased expression over the histopathological grade and lymph node metastasis state. PCR results displayed that none of the samples from oral premalignant lesions showed abnormal changes, while 3 of the OSCC (9.38%) showed loss of heterozygosity (LOH) and 2 (6.25%) with microsatellite instability (MSI). Those 3 samples of LOH showed absent ATM expression.

CONCLUSION

These findings indicated that the over expression of ATM may contribute to prevent carcinogenesis of OSCC. ATM inactivation may be one of the genetic alterations of the molecular progression of OSCC.

[A case report on canceration of proliferative verrucous leukoplakia]

Proliferative verrucous leukoplakia (PVL) is a particular form of oral leukoplakia clinically characterized by chronic proliferation, multiple occurrence, and intractability. It is seen mostly among elderly women and often involves bucca, palate, gingiva and tongue. Its canceration rate is very high. This article reports a case of a middle-aged woman with progressive PVL which became focally malignant who complained about buccal and palatal exophytic white patches, and discusses the possible pathogenic mechanism, diagnosis, treatment, prognosis of PVL and differentiation between PVL and other types of oral leukoplakia by way of reviewing relevant literature.

Expression of viral and human dUTPase in Epstein-Barr virus-associated diseases

Deoxyuridine triphosphatase (dUTPase) catalyses the hydrolysis of dUTP to dUMP and pyrophosphate thus preventing the incorporation of uracil into replicating DNA. Previous studies of several virus models have suggested that viral dUTPases may be required for virus replication in resting cells whereas in proliferating cells cellular dUTPase may substitute for a mutant viral protein. Using monoclonal antibodies and immunohistochemistry, Epstein-Barr virus-associated non-neoplastic and neoplastic diseases were studied for the expression of viral and human dUTPases. Oral hairy leukoplakia, an AIDS-associated lesion of the tongue, is known to support EBV replication in the upper epithelial cell layers. In agreement with this, strong focal expression of EBV dUTPase was detected in the upper epithelial cell layers of oral hairy leukoplakia whereas expression of human dUTPase was confined to the basal proliferative cell compartment. Furthermore, in infectious mononucleosis tonsils, rare scattered small lymphoid cells expressed EBV dUTPase, consistent with the expression pattern of other EBV lytic cycle antigens. These findings are in agreement with the notion that EBV replicates in resting cells. Three EBV-associated tumours, Hodgkin lymphoma, Burkitt lymphoma and nasopharyngeal carcinoma, lacked detectable expression of EBV dUTPase, in agreement with the notion that EBV infection is largely latent in these tumours. By contrast, expression of human dUTPase was observed regularly in these tumours. These results suggest that EBV dUTPase may be a suitable target for anti-viral therapy and that inhibitors of human dUTPase should prove useful for the treatment of human tumours, including EBV-associated cancers.

Laryngeal precancer: a review of the literature, commentary, and comparison with oral leukoplakia

Laryngeal keratosis (LK) is a precancerous mucosal change with great similarity to oral leukoplakia. Its malignant transformation rate varies from 1% to 40%, with the highest rates being found in patients microscopically diagnosed as "keratosis with atypia" (KWA). Recent evidence indicates that even cases with only mild or moderate epithelial dysplasias are at increased risk for malignant transformation, with the highest rates occurring in patients with more severe dysplasia or carcinoma in situ. Approximately 81% of LK patients are men and the average age at diagnosis is 50 years, a decade younger than that for laryngeal carcinoma patients. A high proportion of LK patients are tobacco smokers (84%) and alcohol abusers (at least 35%). LK is almost always found on the true vocal cords and is usually bilateral (67%). Clinical signs of high risk include, in decreasing order of importance: erythroplakia, surface granularity, increased keratin thickness, increased size, recurrence after conservative removal, and long duration. The annual incidence of LK in the United States is 10.2 and 2.1 lesions per 100,000 males and females, respectively.

[Hairy leukoplakia: current concepts]

Current data about oral hairy leukoplakia are reported. Clinical manifestations, histological and ultrastructural features and pathogenic mechanisms are firstly described. Then diagnosis are exposed. Finally, management is discussed.