Odontogenic keratocysts: a clinical and histologic comparison of the parakeratin and orthokeratin variants

Multilocular Radiolucent Pathology in the Body and Ramus of the Mandible: A Case Report

Odontogenic keratocyst (OKC), a type of epithelial developmental cyst, is frequently found in the jaw region. It has invasive characteristics such as satellite cysts, rapid progression, and tissue expansion. The OKC often favors the mandibular angle and ascending ramus. OKC symptoms include pain, swelling, displacement or malpositioning of adjacent teeth, and erosion or thinning of the limited or no bucco-lingual cortical expansion. There is radiographic evidence of a distinct, often scalloped, radiolucent lesion with a characteristic "soap bubble" or "honeycomb" appearance. This article reports a female patient, aged 40 years, with the main concern of unilateral pain and swelling of the mandibular left side and the provisional diagnosis of ameloblastoma. After histopathological examination, the final diagnosis of the patient was OKC. This article also includes previously published literature on OKC with differential diagnosis and relevant clinical and radiologic findings of the case.

How reliable are follow-up studies on odontogenic keratocysts?

Follow-up studies on odontogenic keratocysts have reported widely varying recurrence rates. This raises the question of how reliable these studies are and how the results should be interpreted. The aim of this study was to critically assess the information from all follow-up studies published since 2004 against a set of criteria to determine how thorough the study was. These criteria include the exclusion of the orthokeratinized variant, exclusion of cysts associated with nevoid basal cell carcinoma syndrome, and appropriate reporting of dropouts. A search of four electronic databases covering the years 2004-2022 was performed. Only studies with a sufficient follow-up period (covering a range of 1-8 years) were included. Studies with fewer than 40 cases were excluded. Fourteen relevant studies were identified in the literature search. The vast majority of these studies had considerable shortcomings, giving rise to serious doubts about the validity of their recurrence rate results. Of note, these studies have often been included in meta-analyses that report on the best treatment options to reduce the tendency of recurrences. The results of this review strongly suggest that multicentre studies with strict protocols should be performed to advance knowledge of the presentation of recurrences, both the timing and frequency.

Diagnostic efficacy of apparent diffusion coefficient, texture features, and their combination for differential diagnosis of odontogenic cysts and tumors

OBJECTIVE

This study assessed the diagnostic efficacy of apparent diffusion coefficient (ADC), texture features, and their combination for the differential diagnosis of odontogenic cysts and tumors with cyst-like features.

STUDY DESIGN

In total, 14 dentigerous cysts (DCs), 12 odontogenic keratocysts (OKCs), and 6 unicystic ameloblastomas (UABs) were used as predictor variables in 32 outpatients who underwent magnetic resonance imaging. The outcome variables were ADC, texture features, and their combination for each lesion. Texture features including histogram and gray-level co-occurrence matrix (GLCM) were measured on ADC maps. Ten features were selected by using the Fisher coefficient method. The Kruskal-Wallis test and post hoc Mann-Whitney test with Bonferroni adjustment were used to analyze trivariate statistics. Statistical significance was established at P < .05. Receiver operating characteristic analysis was used to evaluate the diagnostic effect of ADC, texture features, and their combination in distinguishing the lesions from each other.

RESULTS

Apparent diffusion coefficient, 1 histogram feature, 9 GLCM features, and their combination demonstrated significant differences between DC, OKC, and UAB (P ≤ .01). Receiver operating characteristic analysis revealed a high area under the curve of .95 to 1.00 for ADC, 10 texture features, and their combination. Sensitivity, specificity, and accuracy ranged from .86 to 1.00.

CONCLUSIONS

Apparent diffusion coefficient and texture features, alone or in combination, can be clinically important in facilitating the distinction between these odontogenic lesions.

Orthokeratinized odontogenic cysts: A clinicopathologic study of 159 cases and molecular evidence for the absence of PTCH1 mutations

BACKGROUND

Orthokeratinized odontogenic cyst (OOC), a newly designated entity of odontogenic cysts, is an intraosseous jaw cyst that is entirely or predominantly lined by orthokeratinized squamous epithelium. The aim of this study was to report a large series of OOC to substantiate its clinicopathologic profiles and to investigate PTCH1 mutations in OOCs.

METHOD

The clinicopathologic features of 167 OOCs from 159 patients were analyzed and the immunohistochemical expression of markers related to cell differentiation and proliferation was evaluated. Furthermore, PTCH1 mutations were analyzed in 14 fresh samples of OOC.

RESULTS

OOCs occurred mostly in the third and fourth decades (60.4%) with a male predilection (66.7%). The lesions developed more often in the mandible than maxilla, primarily in the posterior mandible and ramus. Eight patients (5.0%) showed multiple locations of either bilateral posterior mandible (n = 6) or both the maxilla and mandible. Radiographically, the majority of OOCs (91.2%) showed a well-demarcated, unilocular radiolucency with 14 multilocular cases (8.8%). A follow-up of 131 patients (123 treated by enucleation with or without marsupialization and eight by peripheral ostectomy) revealed no recurrence during an average period of 4.56 years after surgery. Immunohistochemistry indicated lower proliferative activity and a varying epithelial differentiation pattern in OOC compared with odontogenic keratocysts (OKC). No PTCH1 mutation was detected, except for three known single nucleotide polymorphisms.

CONCLUSION

The clinicopathological and molecular differences between OOC and OKC justified their separation, and unlike OKCs, OOCs did not harbor PTCH1 mutations, suggesting different pathogenesis underlying these two jaw cysts.

Orthokeratinized versus parakeratinized odontogenic keratocyst: Our institutional experience

Introduction

The odontogenic keratocyst (OKC) is quite unique among odontogenic cysts in its specific histological features and in clinical characteristics. The OKC has two variants orthokeratinized odontogenic cyst (OOC) and parakeratinized odontogenic cyst (POC), and POC is considered to be more aggressive and has a high recurrence rate. Therefore, OKC has generated considerable controversy with regard to its true nature.

Aim

The purpose of this study was to determine the differences between POC and OOC variants of odontogenic cysts on the basis of clinical as well as radiological features.

Materials and Methods

A total of 85 cases were included in the present study. There was a marked difference in the age of occurrence, sex, location and radiological presentation of both these entities.

Results

Our institutional experience suggests that POC is more common than OOC and both the variants were commonly found in males. Most of the cases of POC were found in the third decade of life and most of the cases of OOC were frequently seen in the second, fourth and fifth decades. Mandibular posterior area was frequently occurring in both variants. Left side involvement was seen in maxilla and right side in mandible in both variants. Most of the cases were clinically diagnosed as OKC.

Conclusion

The treatment and prognosis varies in both the variants of OKC, hence such epidemiological studies are helpful to ensure proper treatment for these distinct entities.

Incidental finding of orthokeratinized odontogenic cyst with unusual features

Orthokeratinized odontogenic cyst (OOC) is a rare developmental odontogenic cyst occurring in the jaw with debated etiology. It was originally believed to be a variant of odontogenic keratocyst (OKC) but is now considered to be a distinct entity. The majority of the cases occur in the third and fourth decades of life. The common site is the mandibular posterior region with a male predilection. Swelling is the most common symptom which may be accompanied by pain, although in most cases, the lesion is asymptomatic. These lesions mostly present as unilocular radiolucency often associated with an impacted tooth. They may mimic dentigerous cyst and OKC in radiologic and histopathologic presentation, however, differ in biological behavior, pathogenesis and prognosis in comparison. Hence, making an accurate diagnosis is essential. This article describes an incidental finding of OOC in a 28-year-old female during radiographic investigation for orthodontic treatment. This case showed some rare features such as multilocular radiolucency, nonkeratinized epithelium in areas of inflammation, few cholesterol clefts with giant cells, presence of dentinoid-like material and dystrophic calcification in the capsule.

Surgical management of the odontogenic keratocyst: A 20-year experience

The objective of this study was to describe the authors' long-term experience with the management of odontogenic keratocysts (OKCs). All OKC cases treated at the study centre between 1999 and 2015, with a minimum of 5 years of follow-up by December 2019, were reviewed retrospectively. Operative procedures including decompression/marsupialization, enucleation (E), E+Carnoy's solution (CS), E+CS+peripheral ostectomy (PO), and resection were assessed for complete resolution, partial resolution, and recurrence rates. In the parakeratinized non-syndromic group, E+CS+PO resulted in the lowest recurrence rate among the minimally invasive procedures (4.3%), while enucleation resulted in the highest rate (60%). Regarding the other modalities, recurrence was 12.5% for decompression, 11.5% for marsupialization, 16.7% for E+CS, 26.7% for E+PO, and 0% for resection. In the syndromic group, marsupialization resulted in a significantly higher recurrence (23.1%), while E+CS+PO cases showed no recurrence. No recurrence was observed in the orthokeratinized group patients treated with marsupialization or with E+CS. Based on clinico-radiographic features and observed results, it is concluded that OKC, although having a high recurrence rate, is a benign lesion and responds well to conservative procedures in most cases. Radical procedures should be reserved for unresponsive lesions and those with extensive tissue destruction.

Sub-epithelial hyalinization, incomplete cystic lining, and corrugated surface could be a predictor of recurrence in Odontogenic Keratocysts

BACKGROUND

Odontogenic Keratocysts (OKCs) are known for their rapid growth and tendency to invade the adjacent tissues. Its high recurrence rate (2.5%-62%) has attracted many kinds of research to identify new parameters to predict recurrence that would enable better treatment outcomes for such patients. The present study aims to correlate Sub-Epithelial Hyalinization (SEH) that has not been explored in an Asian population to date and other histopathologic features of OKC to its recurrence propensity.

MATERIALS & METHODS

A total of 60 OKCs were analyzed for histopathologic correlation of thickness of lining, complete/incomplete lining, corrugated surface, ortho/para keratinization, intercellular edema, reversed polarity, basilar hyperplasia, the palisading arrangement of basal cells, presence/absence of rete pegs, folding of the epithelium, epithelial/connective tissue separation, SEH, basal offshoots, daughter cysts and inflammation with recurrence to arrive at the most significant histologic feature predicting recurrence.

RESULTS

The most significant histologic parameter differentiating recurrent and non-recurrent OKCs was the presence of SEH (p = 0.004), incomplete lining epithelium (p ​= ​0.023), and a corrugated surface (p ​= ​0.049). Several other histologic parameters evaluated did not statistically correlate with recurrence, this can be attributed to the smaller sample size considered in the present study.

CONCLUSION

SEH is a reliable histologic parameter to predict recurrence in OKCs. The presence of SEH is indicative of a higher recurrence potential in OKCs. Evaluation of histological parameters and their correlation with recurrence in OKCs on a larger sample size could validate the results of the current study undertaken and potentially unravel more insights on predicting recurrence.

KEY MESSAGES

Sub-epithelial hyalinization is a significant feature for predicting recurrence in OKC.

Recurrence of odontogenic keratocysts and possible prognostic factors: Review of 455 patients

BACKGROUND

To describe epidemiological features of 565 Chinese patients with odontogenic keratocysts (OKC), to investigate possible prognostic factors related to recurrence, and to analyse features of recurrent OKC (rOKC).

MATERIAL AND METHODS

A retrospective chart review of 565 cases of OKC treated between 2003 and 2015 was undertaken. The probability of recurrence related to prognostic factors including large size, cortical perforation combined with involved teeth in the lumen of the cyst, inflammation, sites of the involved lesion, sex, and daughter cyst variables were analysed. The subsequent relapse of each OKC was compared.

RESULTS

Patients ranged in age from 7 to 81 years (mean age, 28.4 years) and, of those affected, 66.9% were male and 33.1% were female. Mandibular OKC occurred in 63.01% and 36.99% occurred in the maxilla, 80.53% of patients had non-rOKC, 10.44% rOKC, and 9.03% had multiple OKC lesions. Enucleation with preservation of the involved teeth in the cystic lesion combined with cortical perforation was statistically associated with high recurrence rate, as were daughter cysts, and multilocular lesions. The number of recurrences and the average time (in years) to relapse decreased from the first relapse of OKC to the third relapse, and the difference was significant (P<.05).

CONCLUSIONS

Preservation of the involved teeth combined with cortical perforation appeared to be a potential prognostic factor associated with high recurrence. The follow-up evaluation period for rOKC with ≥ 2 previous treatments should be shorter than for first-time rOKC. The decreasing average duration (years postoperatively) to relapse was related to the number of rOKCs, timing of relapse, and rOKC type.

Multiple Orthokeratinized Odontogenic Cysts: A Report of Two Cases and Review of the Literature

Orthokeratinized odontogenic cysts (OOC) are developmental odontogenic cysts characterised by an orthokeratinized stratified squamous epithelial lining. They were originally believed to be part of the spectrum of Odontogenic Keratocyst, but are now considered to be a distinct entity. They are rare, making up approximately 1% of all odontogenic cysts and they usually occur singly. In this paper we present two new cases of multiple OOCs, and compare them to previous case reports of multiple lesions. The clinical and pathological features are discussed, along with possible diagnostic pitfalls.

Investigation of Postoperative Complications of Intrabony Cystic Lesions in the Oral and Maxillofacial Region

PURPOSE

The purpose of this study was to identify factors that can complicate the surgical removal of intrabony cysts and any relevant correlations between them.

PATIENTS AND METHODS

The medical records of 249 patients who underwent surgical removal of intrabony cysts were retrospectively reviewed. Outcome variables were postoperative complications, infection, and recurrence. Predictor variables were patient age, gender, comorbidities, anatomic location, pathologic diagnosis, preoperative infection, previous marsupialization, and bone graft methods. Logistic regression analysis was performed to identify risk factors of postoperative infection and recurrence.

RESULTS

The cystic lesion was smallest in patients who did not receive a bone graft and increased steadily in those who received a xenogeneic bone graft and an autogenous bone graft, in that order. Paresthesia occurred after enucleation of the cystic lesion in 38 cases. Pathologic fractures were observed in 4 cases. There were 59 postoperative infections. The postoperative infection rate was as high as 63.6% in patients who underwent autogenous bone grafting. In contrast, infection rates were as low as 26.8 and 19.5% in those who underwent xenogeneic bone grafting and no bone grafting, respectively. Location of the cystic lesion in the maxilla or mandible affected the infection rate. When cysts were located in the anterior mandible, no postoperative infection occurred. In contrast, the infection rate was highest for cysts in the mandibular ramus, followed by those in the posterior mandible. Cystic lesion recurrence was observed in 7 cases: 5 cases of odontogenic keratocysts, 1 case of periapical cyst, and 1 case of dentigerous cyst. These findings suggest that cyst pathologic identity affects the recurrence rate. Cyst size was meaningfully correlated with recurrence rate.

CONCLUSIONS

These results suggest that autogenous bone grafts increase the risk of postoperative infection compared with absence of a bone graft.

Use of Virtual Surgical Planning as an Adjunct for Enucleation of Multiple Recurrent Odontogenic Keratocysts: Case Report

This case report describes an interesting use of virtual surgical planning to fabricate tooth-borne cutting guides to assist in localization and enucleation of multiple recurrent odontogenic keratocysts close to the inferior alveolar nerve. The 3-dimensional models generated and cutting guides increased the accuracy and precision of the procedure and decreased surgical time and potential patient morbidity.

Orthokeratinized odontogenic cysts: a Spanish tertiary care centre study based on HPV DNA detection

Background

The role of human papillomavirus (HPV) in orthokeratinized odontogenic cysts (OOCs) has rarely been studied. The objective is to describe the clinicopathological findings in a series of OOCs from a Spanish population that were investigated in relation to the possible presence of HPV.

Methods

A clinicopathological retrospective analysis followed by a molecular analysis of 28 high- and low-risk HPV genotypes was performed in OOC samples of patients seen during the last 15-years in a Spanish tertiary care center.

Results

Of 115 odontogenic cysts with keratinization, 16 cases of OOCs were confirmed and evaluated. OOCs occurred predominantly in the mandible of males (mean age 36.06 ± 13.16 years). Swelling of the jaw followed by pain were the most common clinical symptoms, and 56.5% of the OOC cases were associated with an unerupted tooth. After a mean post-cystectomy follow-up of 3.8 years, only one recurrent case was observed, resulting in a verrucous cystic lesion that was considered premalignant after immunohistological examination. DNA extraction was successful from 14 of the 16 OOC cases. None of the primary OCCs or the single recurrent OOC were positive for HPV in the molecular analysis.

Conclusions

OOCs show a very limited potential for recurrence. Our results suggest that neither high- or low-risk HPV subtypes are likely to play a role in the etiology or neoplastic transformation of OOC, at least in the Spanish population.

The Clinical Features and Expression of bcl-2, Cyclin D1, p53, and Proliferating Cell Nuclear Antigen in Syndromic and Nonsyndromic Keratocystic Odontogenic Tumor

The aim of this study was to describe the clinical features and expression of bcl-2, cyclin D1, p53, and proliferating cell nuclear antigen (PCNA) antibodies in syndromic (nevoid basal cell carcinoma syndrome [NBCCS]) and nonsyndromic patients diagnosed with keratocystic odontogenic tumor (KCOT).

METHODS

This descriptive study comprised 5 patients of KCOT associated with NBCCS and 8 patients of nonsyndromic type treated in the Department of Oral Maxillofacial Surgery, Universiti Kebangsaan Malaysia Medical Centre between years 1998 and 2011. The clinical features (site, size, treatment, and recurrence), demographic characteristics, and immunohistochemistry results using antibodies of bcl-2, cyclin D1, p53, and PCNA were examined. The association of the antibody expression and the type of KCOT was analyzed using Fisher exact test.

RESULTS

Altogether there were 13 patients, 5 with syndromic KCOT (1 patient met 3 major criteria of NBCCS) and 8 with sporadic KCOT. The age range for syndromic KCT was 11 to 21 years (mean 16.00 years, SD 4.36) and 10 to 54 years (median 24.50 years, interquartile range 19.00) for the nonsyndromic KCOT. Tumor recurrence occurred in 3 patients (7.7%); 1 patient from the syndromic and 2 patients from the nonsyndromic. The most positive expression was observed in PCNA for both the syndromic and nonsyndromic samples and the least positive expression involved the p53.

CONCLUSION

PCNA, bcl-2 protein, and cyclin D1 expressions could be useful in evaluating the proliferative activity of the tumor and the aggressiveness of the clinical presentation; however, the authors would propose for larger sample size research for more definitive results.

Use of refrigerant spray of a propane/butane/isobutane gas mixture in the management of keratocystic odontogenic tumors: a preliminary study

PURPOSE

Keratocystic odontogenic tumor (KCOT) is an aggressive benign tumor and the management by complete enucleation followed by cryotherapy maintains the inorganic bone matrix, resulting in better repair and reduces the rates of recurrence. A refrigerant spray with a propane/butane/isobutane gas mixture has been pointed to as an alternative to liquid nitrogen, because the device is easy to handle and contain within the cavity, providing better control and lower risk of injury to the adjacent soft tissue. Thus, the aim of this study was to evaluate the outcome of enucleation followed by cryosurgery using a refrigerant spray of this gas mixture in ten patients diagnosed with KCOT.

METHOD

The biggest lesions received a prior treatment consisting of marsupialization to decrease the tumor size. During the surgeries, the lesions were removed by enucleation and the surgical site was sprayed with the gas mixture.

RESULTS

Wound dehiscence was observed in all cases, which healed by the second intention. The mean follow-up period was 64.3 months (range 24-120 months). Eight of the ten patients showed no evidence of clinical or radiographic recurrence. Pathologic fractures and infections were not observed.

CONCLUSIONS

The results obtained suggest that enucleation followed by cryosurgery is an effective therapy for managing KCOT.

A comparative study of odontogenic keratocyst and orthokeratinized odontogenic cyst using Ki67 and α smooth muscle actin

Aim

This study aimed to demonstrate and evaluate the expression of stromal myofibroblasts (MFs) and epithelial cell proliferation using α-smooth muscle actin (α-SMA) and Ki67 markers, respectively, in odontogenic keratocyst (OKC) and orthokeratinized odontogenic cyst (OOC) to correlate their aggressive behavior.

Materials and Methods

Twenty cases of OKC and twenty cases of OOC were stained with α-SMA and Ki67 markers for demonstration of stromal MFs and epithelial cell proliferation, respectively, and ten cases of well-differentiated squamous cell carcinoma were used as positive control. Assessment of the number of α-SMA-positive stromal cells and Ki67-positive epithelial cells determined by MFs and proliferative epithelial cell frequency in 10 high-power fields (×400) was presented as the mean number of positive cells per field.

Statistical Analysis

Kruskal-Wallis and Mann-Whitney test were used to analyze the difference in the mean number of α-SMA- and Ki67-positive cells per field between OKC and OOC.

Results

The mean number of positively stained cells for α-SMA and Ki67 is significantly higher in OKC compared to OOC.

Conclusion

Impression is that, the different behaviors of these two entities are compatible with their immunohistochemical view. The high value of stromal MFs and proliferative epithelial cells in OKC in comparison to OOC indicates its aggressiveness and potential for recurrence.

p53, p63 and p73 expression and angiogenesis in keratocystic odontogenic tumors

Background

Keratocystic odontogenic tumors (KCOTSs) are odontogenic tumors previously referred to as odontogenic keratocysts. Several studies have reported that KCOT behavior is more like that of a benign neoplasm than a cyst. KCOTs are locally destructive and exhibit a high recurrence rate. The objective of this study is to characterize the expression of p53, p63 and p73 in KCOTs together with the relationship between their expression and KCOT angiogenesis and recurrence.

Material and Methods

Standard indirect immunohistochemistry using monoclonal antibodies specific to human p53, p63, p73 and CD105 was performed in formalin-fixed paraffin-embedded tissue sections of 39 KCOT samples. Grading of p53, p63 and p73 immunohistochemical staining was divided into three groups, whereas microvessel density (MVD) was presented as the mean +/- standard deviation. Associations between p53, p63 and p73 expression and clinical-pathological parameters were analyzed by Fisher’s exact test, whereas associations among MVD levels, clinical and pathological parameters and p53, p63 and p73 expression were analyzed by the Mann-Whitney U test. Correlations among p53, p63, p73 and MVD levels were analyzed using Spearman’s correlation coefficients. For all analyses, p< 0.05 was considered to indicate statistical significance.

Results

p53, p63 and p73 expression was noted in 23, 32 and 26 of 39 KCOT cases, respectively. The mean MVD was 26.7 ± 15.8 per high-power field. In addition, correlations between the expression levels of p53, p63, p73 and MVD in KCOT were examined. Statistically significant positive relationships were noted for all proteins (p<0.001).

Conclusions

Three members of the p53 protein family are expressed in KCOTs, and their expression relates to angiogenesis in these tumors.

Key words:p53, p63, p73, angiogenesis, keratocystic odontogenic tumors.

Odontogenic Cysts and Tumors

This article presents various odontogenic cysts and tumors, including periapical cysts, dentigerous cysts, odontogenic keratocysts, orthokeratinized odontogenic cysts, lateral periodontal cysts, glandular odontogenic cysts, ameloblastomas, clear cell odontogenic carcinomas, adenomatoid odontogenic tumors, calcifying epithelial odontogenic tumors, squamous odontogenic tumors, ameloblastic fibromas, ameloblastic fibro-odontomas, odontomas, calcifying cystic odontogenic tumors, and odontogenic myxomas. The authors provide an overview of these cysts and tumors, with microsopic features, gross features, differential diagnosis, prognosis, and potential diagnostic pitfalls.

Multiple orthokeratinized odontogenic cysts: a case report

The purpose of this report is to document the clinical, radiographic, pathological and molecular findings of the first case of multiple orthokeratinized odontogenic cysts (OOCs). Multiple odontogenic keratocysts are one of the major features of nevoid basal cell carcinoma syndrome (NBCCS), and loss of heterozygosity in the PTCH gene, the culprit gene for NBCCS, has recently been found in sporadic OOC cases. Therefore, in this presenting case, we also investigated the possibility that this patient might also have NBCCS, by comparing the available clinical information and the molecular findings of this case to the diagnostic criteria for NBCCS (as proposed by the First International Colloquium on NBCCS in 2011). However, this patient with multiple OOCs showed no evidence of having NBCCS. This conclusion supports the findings from previous case series based on sporadic cases that OOC does not appear to be associated with NBCCS.

Decompression for management of keratocystic odontogenic tumor in the mandible

Keratocystic odontogenic tumor (KCOT) is a benign intraosseous neoplasm of odontogenic origin with high recurrence rate. To date, various conservative or aggressive management strategies have been suggested as a method of treatment. Decompression is a conservative method that has been used in the treatment of large odontogenic cysts. The present paper reports a case of KCOT located in the mandible and discusses the importance of its management using conservative methods. The authors present a case of a 38-year-old patient with a KCOT located in the right mandibular angle and ascending ramus, which was treated by decompression followed by enucleation and curettage. The lesion did not recur during a follow-up period of 3 years after surgery. Preserving important structures of the bone and soft tissue decompression is a method with low morbidity. In addition, according to the literature, decompression has a success rate at least as high as the one of most aggressive treatments.

Evaluation of stromal myofibroblasts expression in keratocystic odontogenic tumor and orthokeratinized odontogenic cysts: A comparative study

Objective:

Keratocystic odontogenic tumor (KCOT) has an aggressive clinical course and a high tendency of recurrence, while orthokeratinized odontogenic cyst (OOC) has different characteristics and does not show aggressive behaviour. Even the treatment of these two lesions varies considerably. A large number of epithelial molecules have been studied in order to differentiate odontogenic keratocyst (OKC) from OOC, but stromal factors have not been adequately studied. Recently, tumor stroma has evolved as a particular field of interest. In the present study, we aim to evaluate and compare the expression of stromal myofibroblasts (MFs) in these entities and correlate it to its aggressive behavior. The term ‘keratocystic odontogenic tumor’ has been introduced by WHO in 2005 for odontogenic keratocyst keeping in mind its aggressive behavior, however still many pathologists and clinicians use the term OKC synonymously.

Materials and Methods:

A total of 10 cases of KCOT and 10 cases of OOC were stained for alpha-smooth muscle actin (αSMA) for demonstration of stromal MFs. MF frequency was assessed as the number of αSMA-positive stromal cells in 10 high power fields, presented as the mean number of positive cells per field.

Results:

Counts showed that the mean number of positive cells in KCOT (20.6 ± 2.05) was significantly higher than that seen in OOC (10.4 ± 1.06) (P < 0.05).

Conclusion:

The different behaviors of these lesions are compatible with the finding of the present study. The increased number of stromal MFs in KCOT in comparison to OOC correlates with its aggressive behavior and increased tendency towards recurrence.

Orthokeratinised odontogenic cyst mimicking periapical cyst

Orthokeratinised odontogenic cyst (OOC) denotes the odontogenic cyst that microscopically has an orthokeratinised epithelial lining. OOC is characterised by a less-aggressive behaviour and a low rate of recurrence. This report describes a case of OOC involving posterior part of the mandible that mimicked periapical cyst in a 14-year-old boy. The initial clinical diagnosis was given as periapical cyst based on the clinical and radiographical features. Enucleation of the cyst was performed and the specimen was sent for histopathological examination. A definite diagnosis of OOC was made by histopathological examination of the biopsy specimen. This case emphases on including OOC in the differential diagnosis of radiolucencies occurring in the periapical region of non-vital tooth.

Orthokeratinized odontogenic cyst: a report of three clinical cases

The orthokeratinized odontogenic cyst (OOC) is a rare developmental odontogenic cyst that has been considered as a variant of the keratocystic odontogenic tumour (KCOT) until Wright (1981) defined it as a different entity. Surgery is the usual treatment, and recurrence or association with Gorlin-Goltz syndrome has rarely been described. In this report, we presented three cases of this pathology, and we review the principal clinical, histological, radiological, and therapeutic aspects. Case 1. A 73-year-old female presents with a slight swelling on the right mandible, associated with an unilocular well-defined radiolucent lesion. Case 2. A 27-year-old female presents with a painful mandibular swelling associated with an unilocular radiolucent lesion posterior to the 4.8. Case 3. A 61-year-old male was casually detected presents with an unilocular radiolucent lesion distal to the 4.8. Conclusion. The OOC is a specific odontogenic clinicopathological entity that should be differentiated from the KCOT as it presents a completely different biological behaviour.

The relationship between radiological features and clinical manifestation and dental expenses of keratocystic odontogenic tumor

Purpose

This study was performed to identify correlations between keratocystic odontogenic tumor (KCOT) data from CT sections, and data on the KCOT clinical manifestation and resulting dental expenses.

Materials and Methods

Following local Institutional Review Board (IRB) approval, a seven-years of retrospective study was performed regarding patients with KCOTs treated at the Seoul National University Dental Hospital. A total of 180 KCOT were included in this study. The following information was collected: age, gender, location and size of the lesion, radiological features, surgical treatment provided and dental expenses.

Results

There was no significant association between the size of the KCOT and age, gender, and presenting preoperative symptoms. In both jaws, it was unusual to find KCOTs under 10 mm. The correlation between the number of teeth removed and the size of the KCOT in the tooth bearing area was statistically significant in the mandible, whereas in the maxilla, no significant relationship was found. Dental expenses compared with the size of the KCOT were found to be significant in both jaws.

Conclusion

The size of KCOT was associated with a significant increase in dental expenses for both jaws and the number of teeth removed from the mandible. These findings emphasize the importance of routine examinations and early detection of lesions, which in turn helps preserving anatomical structures and reducing dental expenses.

Keratocystic odontogenic tumor: systematic review with analysis of 72 additional cases from Mumbai, India

OBJECTIVE

The aim of this systematic review was to assess the clinical and imaging findings of keratocystic odontogenic tumor (KOT). This article also attempts to determine the prevalence of KOTs and orthokeratinized odontogenic cyst (OOC) in the western Indian population and to compare demographic and radiographic findings of KOT of our cohort with that of the rest of the world.

STUDY DESIGN

Relevant publications on KOT were reviewed from the published literature from 1976 to March 2012. Data regarding the 72 additional cases from Mumbai also were analyzed.

RESULTS

Sixty-five reports were identified for this systematic review. The findings were divided into 4 global groups for analysis. The prevalence of KOT was 0.0173% and that of OOC 0.0012%. Male sex, mandible, and the unilocular variation were predominant for the additional cases.

CONCLUSIONS

The characterization of the KOT lesions was accomplished, taking into consideration the variations to the western Indian population.

Recurrent keratocystic odontogenic tumor in the masseter muscle overlying the boney perforations: a case report

Keratocystic odontogenic tumor (KCOT) is a benign intraosseous neoplasm of odontogenic origin with high recurrence rates and tendency to invade adjacent tissue. Most recurrences occur in the first 5 years after surgery and are usually located at the site of the primary tumor in the jaws. We report a rare case of KCOT which recurred in the masseter muscle 14 years after segmental mandibulectomy and autogenous frozen lesional mandible reimplantation. The patient had undergone enucleation of KCOT in the right mandible 20 years before segmental mandibulectomy. This case could further demonstrate the aggressive behavior of KCOT.

Non-syndromic odontogenic keratocysts: A rare case report

Odontogenic keratocysts are very well documented in the literature. Multiple odontogenic keratocysts (OKCs) are one of the most frequent features of nevoid basal cell carcinoma syndrome (NBCCS). It is linked with mutation in the PTCH gene (human homolog of the drosophila segment polarity gene, "patched",). Partial expression of the gene may result in occurrence of only multiple recurring OKC without any associated systemic findings. A rare case of multiple odontogenic keratocysts unassociated with any syndrome is reported, so as to add to the growing number of such cases in the literature. The possibility of this case being a partial expression of the Gorlin-Goltz syndrome is discussed.

Keratocystic odontogenic tumours of the jaws and associated pathologies: a 10-year clinicopathologic audit in a referral teaching hospital in Kenya

AIM

To establish the pattern of occurrence and the clinicopathological features of keratocystic odontogenic tumour (KCOT) over a 10-year period.

MATERIALS AND METHOD

Patients from the University of Nairobi Dental Hospital treated for KCOT were included in the study over a 10-year period. The study highlights the demographic, clinico-radiological and histological features of these tumours.

RESULTS

A total of 22 confirmed cases of KCOTs were recorded with equal gender prevalence; (M:F = 1.44:1). The age range of the patients was from 10 to 69 years with a peak in the second decade of life (mean = 27.5 yrs). Of the 22 cases, 15 (68.2%) occurred in the mandible of which eight (53.3%) involved the body, five (33.4%) the angle and ramus. Six (27.3%) occurred in the maxilla, and one (4.5%) was in both jaws and was associated with Gorlin-Goltz Syndrome. The most common presenting complaint in most patients was swelling 54.6%, and in 18.2% was incidental finding. Eight (36.4%) cases showed satellite cysts upon pathologic evaluation. Thirteen (59.1%) cases were managed by surgical excision, while nine (40.9%) were managed by enucleation.

CONCLUSION

Based on the outcome of this study, KCOT present mostly in body, angle and ramus of the mandible and its peak is in the second decade of life.

Novel PTCH1 mutations in patients with keratocystic odontogenic tumors screened for nevoid basal cell carcinoma (NBCC) syndrome

Keratocystic odontogenic tumors (KCOTs) are cystic tumors that arise sporadically or associated with nevoid basal cell carcinoma syndrome (NBCCS). NBCCS is a rare autosomal dominantly inherited disease mainly characterized by multiple basal cell carcinomas, KCOTs of the jaws and a variety of other tumors. PTCH1 mutation can be found both in sporadic or NBCCS associated KCOTs. The aim of the current study was to assess whether a combined clinical and bio-molecular approach could be suitable for the detection of NBCCS among patients with a diagnosis of keratocystic odontogenic tumors (KCOTs). The authors collected keratocystic odontogenic tumors recorded in the database of the Pathology Department of the University of Modena and Reggio Emilia during the period 1991–2011. Through interviews and examinations, family pedigrees were drawn for all patients affected by these odontogenic lesions. We found out that 18 of the 70 patients with KCOTs and/or multiple basal cell carcinomas actually met the clinical criteria for the diagnosis of NBCCS. A wide inter- and intra-familial phenotypic variability was evident in the families. Ameloblastomas (AMLs) were reported in two probands that are also carriers of the PCTH1 germline mutations. Nine germline mutations in the PTCH1 gene, 5 of them novel, were evident in 14 tested probands. The clinical evaluation of the keratocystic odontogenic tumors can be used as screening for the detection of families at risk of NBCCS. Keratocystic odontogenic lesions are uncommon, and their discovery deserves the search for associated cutaneous basal cell carcinomas and other benign and malignant tumors related to NBCCS.

Keratocystic odontogenic tumour (KCOT)--a cyst to a tumour

PURPOSE

The World Health Organization (WHO) has reclassified 'odontogenic keratocyst' (OKC) to 'keratocystic odontogenic tumour' (KCOT) in 2005. Currently, this tumour is classified as a benign neoplasm of odontogenic origin and not as a cyst. This article reviews and discusses history, classification scheme, aetiology and pathogenesis, molecular and genetic basis, incidence, epidemiology and site, clinical features, imaging, histopathology, immunohistochemistry, treatment options, prognosis, recurrence and malignant transformation of KCOT, with emphasis on understanding the basis of reclassification as 'keratocystic odontogenic tumour'.

METHODS

A systematic search and review of the literature was carried out in the online database of the United States National Library of Medicine to identify eligible titles for the study.

RESULTS

Current evidence suggests that the scientific community still continues to use the term 'odontogenic keratocyst' more favourably than 'keratocystic odontogenic tumour'.

CONCLUSION

The online database search indicates that the scientific community still continues to use the term 'odontogenic keratocyst' more favourably than 'keratocystic odontogenic tumour'. At this juncture, where the terminology has changed from a cyst to a tumour, a thorough review of literature on KCOT is presented.

Conservative management of a large keratocystic odontogenic tumor in the maxilla

Keratocystic odontogenic tumor is characterized by high recurrence rates. Conservative or aggressive management has been suggested as a method of treatment. Decompression is a conservative treatment that has been used in the treatment of large odontogenic cysts. The authors report a case of a 14-year-old patient with a keratocystic odontogenic tumor located in the right maxilla, which was treated by decompression followed by enucleation with curettage. The lesion did not recur on follow-up for 3 years after the enucleation surgery.

Recurrent keratocystic odontogenic tumours: report of 19 cases

OBJECTIVES

The aim of this study was to analyse 19 recurrent keratocystic odontogenic tumours (KCOTs).

METHODS

19 patients with recurrent KCOTs were retrospectively analysed. These patients had been treated by either enucleation or a combination of enucleation and Carnoy's solution. The analyses covered major aspects of primary KCOT and/or recurrent KCOT identities, including patient profile, clinical features, histopathology, radiology, treatment and prognosis.

RESULTS

19 (7.4%) out of 257 primary KCOT cases recurred, with an average patient age of 30.5 years (age range 18-45 years). 15 lesions were in the mandible and the remaining 4 were in the maxilla. There were more unilocular than multilocular occurrences for the primary tumours, with a ratio of 2.2:1. These KCOTs were initially treated by simple enucleation (12 cases) or enucleation with Carnoy's solution (7 cases). After the initial surgery, 15 out of 19 (78.9%) recurred within 6 years, while 4 (21.1%) recurred after 6 years. Evidently, the recurrent lesion was involved with the roots of the teeth in three out of six cases whose teeth were preserved. In addition, the recurrent KCOTs had a tendency to be more multilocular or multifocal than the primary cases, with a unilocular-to-multilocular ratio of 1.1:1.

CONCLUSIONS

7.4% of primary KCOTs recurred within 6 years after initial treatment with either enucleation or a combination of enucleation and Carnoy's solution. The recurrent KCOTs were more likely to be multilocular or multifocal than the primary cases and often involved the teeth. The method of operation for these recurrent lesions would be considered as a more aggressive approach.

Conservative management of keratocystic odontogenic tumors of jaws

PURPOSE

The aim of this study was to evaluate different surgical treatment methods for keratocystic odontogenic tumors (KCOTs) and the outcome of those treatments over a 9-year period.

PATIENTS AND METHODS

A retrospective review was performed on 43 KCOTs in 39 patients. In radiographic evaluations for diagnosis, follow ups and before and after treatment, panoramic, 3D CT and MR images were used. The three groups of different surgical treatment were (1) enucleation for small unilocular lesions without certainty of histology; (2) enucleation with Carnoy's solution, for small unilocular lesions after previous histological confirmation of KOCT; (3) marsupialization followed by enucleation with Carnoy's solution implemented for large often multilocular KCOTs with intact or destruction of cortical bone without infiltration of neighbouring tissue.

RESULTS

43 KCOT cases were mostly localized in mandible (76.7%), radiologically unilocular (72%), and parakeratocysts (88.4%). Inflammation and satellite cysts (daughter cysts) were detected histopathologically in 14 (32.5%) and 7 (16.3%), respectively. Among the 43 cysts, 20 (46.5%) were associated with the impacted third molar and of 21 (48.8%) was in tooth bearing area, and 5 (11, 6%) located on edentulous areas. It was located mostly in the anterior region of maxilla (90%) and in mandibular molar and ramus (62.8%). The treatments of KCOTs were 18 (41.9%) for group 1, and 10 (23.3%) group 2, and 15 (34.8%) group 3. A statistically significant relationship was found between the radiographic appearance and treatment methods (P = 0.00). No recurrence was found on 40.54 ± 23.02 months follow up.

CONCLUSION

We concluded that successful treatment methods were enucleation and Carnoy's solution in small lesions and marsupialization in lesions that have reached a very large size, but because KCOT was observed in second decade mostly, long-term follows up are suggested.

Imaging findings in a case of Gorlin-Goltz syndrome: a survey using advanced modalities

Gorlin-Goltz syndrome is an infrequent multi-systemic disease which is characterized by multiple keratocysts in the jaws, calcification of falx cerebri, and basal cell carcinomas. We report a case of Gorlin-Goltz syndrome in a 23-year-old man with emphasis on image findings of keratocyctic odontogenic tumors (KCOTs) on panoramic radiograph, computed tomography, magnetic resonance (MR) imaging, and Ultrasonography (US). In this case, pericoronal lesions were mostly orthokeratinized odontogenic cyst (OOC) concerning the MR and US study, which tended to recur less. The aim of this report was to clarify the characteristic imaging features of the syndrome-related keratocysts that can be used to differentiate KCOT from OOC. Also, our findings suggested that the recurrence rate of KCOTs might be predicted based on their association to teeth.