The odontogenic keratocyst: a 20-year clinicopathologic review

Differential Diagnosis of OKC and SBC on Panoramic Radiographs: Leveraging Deep Learning Algorithms

This study aims to determine whether it can distinguish odontogenic keratocyst (OKC) and simple bone cyst (SBC) based solely on preoperative panoramic radiographs through a deep learning algorithm. (1) Methods: We conducted a retrospective analysis of patient data from January 2018 to December 2022 at Pusan National University Dental Hospital. This study included 63 cases of OKC confirmed by histological examination after surgical excision and 125 cases of SBC that underwent surgical curettage. All panoramic radiographs were obtained utilizing the Proline XC system (Planmeca Co., Helsinki, Finland), which already had diagnostic data on them. The panoramic images were cut into 299 × 299 cropped sizes and divided into 80% training and 20% validation data sets for 5-fold cross-validation. Inception-ResNet-V2 system was adopted to train for OKC and SBC discrimination. (2) Results: The classification network for diagnostic performance evaluation achieved 0.829 accuracy, 0.800 precision, 0.615 recall, and a 0.695 F1 score. (4) Conclusions: The deep learning algorithm demonstrated notable accuracy in distinguishing OKC from SBC, facilitated by CAM visualization. This progress is expected to become an essential resource for clinicians, improving diagnostic and treatment outcomes.

Applying artificial intelligence to detect and analyse oral and maxillofacial bone loss-A scoping review

Radiographic evaluation of bone changes is one of the main tools in the diagnosis of many oral and maxillofacial diseases. However, this approach to assessment has limitations in accuracy, inconsistency and comparatively low diagnostic efficiency. Recently, artificial intelligence (AI)-based algorithms like deep learning networks have been introduced as a solution to overcome these challenges. Based on recent studies, AI can improve the detection accuracy of an expert clinician for periapical pathology, periodontal diseases and their prognostication, as well as peri-implant bone loss. Also, AI has been successfully used to detect and diagnose oral and maxillofacial lesions with a high predictive value. This study aims to review the current evidence on artificial intelligence applications in the detection and analysis of bone loss in the oral and maxillofacial regions.

Emulating Clinical Diagnostic Reasoning for Jaw Cysts with Machine Learning

The detection and classification of cystic lesions of the jaw is of high clinical relevance and represents a topic of interest in medical artificial intelligence research. The human clinical diagnostic reasoning process uses contextual information, including the spatial relation of the detected lesion to other anatomical structures, to establish a preliminary classification. Here, we aimed to emulate clinical diagnostic reasoning step by step by using a combined object detection and image segmentation approach on panoramic radiographs (OPGs). We used a multicenter training dataset of 855 OPGs (all positives) and an evaluation set of 384 OPGs (240 negatives). We further compared our models to an international human control group of ten dental professionals from seven countries. The object detection model achieved an average precision of 0.42 (intersection over union (IoU): 0.50, maximal detections: 100) and an average recall of 0.394 (IoU: 0.50–0.95, maximal detections: 100). The classification model achieved a sensitivity of 0.84 for odontogenic cysts and 0.56 for non-odontogenic cysts as well as a specificity of 0.59 for odontogenic cysts and 0.84 for non-odontogenic cysts (IoU: 0.30). The human control group achieved a sensitivity of 0.70 for odontogenic cysts, 0.44 for non-odontogenic cysts, and 0.56 for OPGs without cysts as well as a specificity of 0.62 for odontogenic cysts, 0.95 for non-odontogenic cysts, and 0.76 for OPGs without cysts. Taken together, our results show that a combined object detection and image segmentation approach is feasible in emulating the human clinical diagnostic reasoning process in classifying cystic lesions of the jaw.

Deep learning based diagnosis for cysts and tumors of jaw with massive healthy samples

We aimed to develop an explainable and reliable method to diagnose cysts and tumors of the jaw with massive panoramic radiographs of healthy peoples based on deep learning, since collecting and labeling massive lesion samples are time-consuming, and existing deep learning-based methods lack explainability. Based on the collected 872 lesion samples and 10,000 healthy samples, a two-branch network was proposed for classifying the cysts and tumors of the jaw. The two-branch network is firstly pretrained on massive panoramic radiographs of healthy peoples, then is trained for classifying the sample categories and segmenting the lesion area. Totally, 200 healthy samples and 87 lesion samples were included in the testing stage. The average accuracy, precision, sensitivity, specificity, and F1 score of classification are 88.72%, 65.81%, 66.56%, 92.66%, and 66.14%, respectively. The average accuracy, precision, sensitivity, specificity, and F1 score of classification will reach 90.66%, 85.23%, 84.27%, 93.50%, and 84.74%, if only classifying the lesion samples and healthy samples. The proposed method showed encouraging performance in the diagnosis of cysts and tumors of the jaw. The classified categories and segmented lesion areas serve as the diagnostic basis for further diagnosis, which provides a reliable tool for diagnosing jaw tumors and cysts.

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.

Deep Learning for Automated Detection of Cyst and Tumors of the Jaw in Panoramic Radiographs

Patients with odontogenic cysts and tumors may have to undergo serious surgery unless the lesion is properly detected at the early stage. The purpose of this study is to evaluate the diagnostic performance of the real-time object detecting deep convolutional neural network You Only Look Once (YOLO) v2—a deep learning algorithm that can both detect and classify an object at the same time—on panoramic radiographs. In this study, 1602 lesions on panoramic radiographs taken from 2010 to 2019 at Yonsei University Dental Hospital were selected as a database. Images were classified and labeled into four categories: dentigerous cysts, odontogenic keratocyst, ameloblastoma, and no lesion. Comparative analysis among three groups (YOLO, oral and maxillofacial surgeons, and general practitioners) was done in terms of precision, recall, accuracy, and F1 score. While YOLO ranked highest among the three groups (precision = 0.707, recall = 0.680), the performance differences between the machine and clinicians were statistically insignificant. The results of this study indicate the usefulness of auto-detecting convolutional networks in certain pathology detection and thus morbidity prevention in the field of oral and maxillofacial surgery.

The presentation of odontogenic keratocysts in the jaws with an emphasis on the tooth-bearing area: a systematic review and meta-analysis

PURPOSE

This study was conducted in order to gain insight in the actual ratio of odontogenic keratocysts occurring in the tooth-bearing area as compared to the posterior region of the jaws in order to come up with reliable data to base upon a rational treatment policy.

METHODS

We searched MEDLINE, Web of Science, Scopus, and Cochrane databases for studies reporting on the location of mandibular and maxillary odontogenic keratocysts. All records were independently assessed and a meta-analysis was performed. Risk difference with a confidence interval of 95% of having the lesion in the posterior region versus the tooth-bearing area was the effect measure. P value for the summary effect of < 0.05 was considered statistically significant.

RESULTS

The 2615 records retrieved were reduced to 34 studies to be qualitatively/quantitatively assessed. The pooled values showed that the difference in the clinical risk of having keratocysts in the posterior region of the mandible and in the tooth-bearing area of the maxilla is 21 and 43%, respectively (P < 0.02 and P < 0.00001).

CONCLUSIONS

A substantial amount of keratocysts occur in the tooth-bearing area of the jaws, requiring attention.

What is the Prevalence of Undiagnosed Nevoid Basal Cell Carcinoma Syndrome in Children With an Odontogenic Keratocyst?

PURPOSE

Odontogenic keratocysts (OKCs) can occur in isolation or as part of nevoid basal cell carcinoma syndrome (NBCCS). Patients with NBCCS are younger at OKC diagnosis than those with nonsyndromic OKC (NS-OKC). The purpose of this study was to determine the prevalence of undiagnosed NBCCS in children who present with an OKC and to assess differences in demographic and presenting features between children with NBCCS and those with NS-OKC.

MATERIALS AND METHODS

This study is a retrospective case series of children with an OKC presenting to Boston Children's Hospital (Boston, MA) from 2007 through 2018. To be included, patients had to be no older than 18 years and have a newly diagnosed OKC. Patients were excluded if they had previous or recurrent OKC or NBCCS diagnosis. Records were reviewed for age at presentation, gender, number and location of OKCs, treatment, recurrence, family history, and clinical features consistent with NBCCS. Descriptive data were summarized.

RESULTS

The sample included 50 patients (27 boys) diagnosed with an OKC at a mean age of 11.7 years (range, 2 to 18 yr); 36% (n = 18) with NBCCS and 64% (n = 32) with NS-OKC. NBCCS diagnosis was made in 8 of 18 patients (44%) because of a family history at presentation, and in 10 patients (56%) the diagnosis was made by genetic testing or documentation of diagnostic criteria. Eight of 18 patients (44%) with undiagnosed NBCCS presented with a single OKC. Patients with NBCCS were significantly younger at presentation (NBCCS, 9.3 yr; NS-OKC, 13.0 yr), had more cysts at time of diagnosis (NBCCS, 1.7; NS-OKC, 1.0; P < .05), had more maxillary cysts (NBCCS, 13; NS-OKC, 11), and had a higher recurrence rate (P < .05).

CONCLUSION

Given the prevalence of undiagnosed NBCCS in children with OKC, clinicians should have a low threshold for referral for complete examination or genetic testing in children with even a single OKC.

Pigmented odontogenic keratocyst: Report of a rare case and review of the literature

Pigmented odontogenic keratocyst (OKC) is very rare and its etiology remains uncertain. To the best of our knowledge, only 9 cases of pigmented OKC have been published in English-language literature. This report describes a pigmented OKC in a 14-year-old black male patient. Radiographically, the lesion appeared as a well-circumscribed, unilocular, and radiolucent image. A surgical excision was performed. Histopathological examination revealed an OKC. Additionally, a brownish, sparsed, intracytoplasmic pigmentation was observed in the basal cell layer, which was positive for Fontana-Masson staining. Immunohistochemistry reactions revealed positive dendritic cells for S-100 protein, HMB45 and Melan A. No clinical and imaging signs of recurrence were observed after 24 months. In conclusion, melanin apparently does not represent a factor for distinct biological behavior in OKC.

Key words:Melanin, melanocytes, odontogenic cyst, odontogenic keratocyst, pigmented.

Odontogenic Keratocyst: Developing a Protocol for Surgical Intervention

The aim of this study was to report the outcome of a conservative treatment protocol – “enucleation and packing open” for odontogenic keratocyst (OKC). Ten patients with OKC were treated at our institute by peripheral ostectomy, enucleation followed by open packing. This conservative treatment protocol was selected because of relatively young age of the patients and relatively large size of the lesions. All the cases were monitored at regular predetermined intervals using clinical evaluation and panoramic radiographs. There was no evidence of recurrence during follow-up. The conservative treatment protocol for OKC, based on enucleation followed by open packing would be a possible choice in view of the simplicity of surgical procedure and low morbidity. This treatment modality has a low recurrence rate and may be particularly useful in young patients and patients with advanced systemic disease not amenable to major surgical intervention.

Recurrence of nonsyndromic odontogenic keratocyst after marsupialization and delayed enucleation vs. enucleation alone: a systematic review and meta-analysis

PURPOSE

This study was conducted in order to determine whether marsupialization before definitive enucleation of nonsyndromic odontogenic keratocysts (OKCs) is capable of decreasing the recurrence rate more effectively than just enucleation.

METHODS

We searched MEDLINE, Web of Science, Scopus, and Cochrane Library, until August 5th of 2017 for original studies reporting on the treatment of OKCs with and without previous marsupialization and the related recurrence rate. All records and data were independently assessed, meta-analysis was performed, and the odds ratio of recurrence was the effect measure; P value for the summary effect of < 0.05 was considered statistically significant.

RESULTS

The 748 records retrieved were reduced to 6 studies to be qualitatively assessed and 5 studies were included in the meta-analysis. The overall odds ratio of 0.57 [0.25-1.28] of the pooled values pointed that marsupialization reduced the recurrence rate in comparison to just enucleation; however, the P value showed that there is no strong evidence to support this statement.

CONCLUSIONS

Marsupialization followed by enucleation after 12 to 18 months reduces the recurrence rate, but more studies are necessary to support this statement.

Squamous cell carcinoma arising within a maxillary odontogenic keratocyst: A rare occurrence

Squamous cell carcinoma (SCC) arising within the lining of an odontogenic keratocyst (OKC) is a rare occurrence. Although potentially locally destructive, OKC is a benign odontogenic process that typically presents with clinical and radiographic features characteristic of a benign intraosseous neoplasm. We present the clinical and radiographic features of a maxillary mass that demonstrated SCC arising from the lining of an OKC. Although the initial clinical and radiographic presentation suggested an infection or malignant neoplasm, biopsies revealed an infiltrative well-differentiated SCC contiguous with and arising from the focus of a pre-existing OKC. The patient subsequently underwent a type II hemi-maxillectomy with neoadjuvant chemoradiation. This report discusses the clinical and radiographic features associated with intraosseous malignancies, especially those arising from an otherwise benign odontogenic lesion. While the majority of OKCs are benign, the current report illustrates the potential for carcinomatous transformation within the lining of an OKC.

A Case of an Extensive Keratocystic Odontogenic Tumor in the Mandible Reconstructed with a Custom-Made Total Joint Prosthesis

The use of virtual surgical planning and computer-aided design/computer-aided manufacturing has previously been reported to enhance the planning for the reconstruction of mandibular continuity defects and to reduce surgical time. Reported is a case of a large keratocystic odontogenic tumor (KOT) affecting right hemimandible including the condylar neck. This case was initially reconstructed with a condyle-bearing reconstruction plate, but because of fatigue fracture 15 years later, a new reconstruction with a custom-made total joint temporomandibular prosthesis was performed.

Diagnosing the most common odontogenic cystic and osseous lesions of the jaws for the practicing pathologist

Odontogenic cysts and osseous lesions are often seen as challenging diagnostic lesions but the majority of them are easily classified. This article outlines the diagnostic features required for separating the most common of odontogenic cysts and select osseous lesions of the jaws. Clinical and radiographic findings of these jaw lesions often lead to a differential diagnosis that only the histologic findings will clarify. Dentigerous cyst, keratocystic odontogenic tumor, and certain ameloblastomas that have cystic change, may have identical radiographic findings, with only separation by their specific histologic features leading to the significantly different treatments required for each. Conversely, some cystic lesions can appear histologically identical and cannot be diagnosed without the radiographic findings. Certain osseous lesions of the jaws are particularly problematic for diagnosis without the appropriate radiographic findings, and the diagnosis should probably not be attempted on the histologic findings alone. This article will integrate the necessary clinical, radiographic, and histologic findings required to address the most common odontogenic lesions.

Medication Management of Jaw Lesions for Dental Patients

Most pathologic lesions of the jaws or of oral mucosa are treated successfully by surgical interventions. For treatment of the central giant cell lesion, aneurysmal bone cysts, histiocytosis of the mandible, hemangioma, odontogenic keratocyst, Paget disease, oral submucous fibrosis, and oral lichen planus, medical management consisting of intralesional injections, sclerosing agents, and systemic bisphosphonates is as successful as surgical procedures with fewer complications. Pharmacology of agents used and protocols are presented.

Keratocystic Odontogenic Tumour with Extraosseal Spread: Evaluation of the Effect Carnoy's Solution

Keratocystic odontogenic tumour is relatively rare benign tumour. It is characterized by its fast aggressive growth and high risk of recurrence. Treatment is always surgical: conservative (enucleation, marsupialization) or aggressive (enucleation followed by application of Carnoy's solution, cryotherapy; peripheral ostectomy or en block resection of the jaw). Authors analysed retrospectively 22 patients who fulfilled inclusion criteria, i.e. had odontogenic keratocystic tumour of mandible, wherein antero-posterior dimension was at least 30 mm, and the tumour penetrated into the surrounding soft tissues. All patients underwent tumour enucleation, in 11 patients Carnoy's solution was given into the bone cavity after enucleation. The recurrence rate in the evaluation at least 36 months after surgery was both patient groups the same: 45.4%.

Conservative Management of Keratocystic Odontogenic Tumour with Enucleation, Excision of the Overlying Mucosa and Electrocauterization - A Case Report

Odontogenic keratocyst remains an enigma for clinicians and researchers, although gains in knowledge in recent years have improved the understanding of this interesting lesion. The diagnostic problems are mainly related to the relative lack of specific clinical and radiographic features that unequivocally point to a proper diagnosis. Of particular interest to clinicians is the biologic behaviour of keratocysts which includes high rates of recurrence and potential existence as a benign odontogenic neoplasm, keratocystic odontogenic tumour. Various surgical modalities have evolved in an attempt to reduce the recurrence rate, including curettage, peripheral ostectomy, removal of overlying mucosa in cases of cortical perforation and osseous resection in the form of marginal or segmental osteotomies. The present case report describes the conservative surgical management of a large keratocystic odontogenic tumour in a young patient with no evidence of recurrence at two years follow-up.

Keratocystic odontogenic tumor invading the maxillary sinus: a case report of collaborative surgery between an oral surgeon and an otorhinolaryngologist

We report a case of keratocystic odontogenic tumor (KCOT) in a 21-year-old female patient. The patient was referred to our clinic from a dental clinic for the radical treatment of recurrent KCOT in the maxilla. She had undergone conservative drainage surgery twice at that clinic.The tumor was cystic and covered with a bony capsule, which extended high into the maxillary sinus. A pinhole fistula, which was created during a previous surgery, was identified in the gingivobuccal sulcus. The whole tumor was successfully removed using a bidirectional approach from the fistula and from the antrostomy in the middle meatus. This report shows that the intimate collaboration between an otorhinolaryngologist and an oral surgeon could provide a minimally invasive, and at the same time, radical surgical treatment for certain kinds of tumor in the head and neck region. We also recommend the introduction of endoscopic surgeries by the oral surgeon.

Malignant transformation of keratocystic odontogenic tumor: two case reports

INTRODUCTION

Keratocystic odontogenic tumors (KCOTs) are cystic tumours originating from the dental lamina of the maxilla and mandible that are lined with keratinized epithelium. While benign, they can be locally destructive and have a high recurrence rate despite treatment. Rarely, KCOTs may undergo malignant transformation into Primary Intraosseous Squamous Cell Carcinoma (PIOSCC).

CASE REPORT

This study reports the clinical findings, radiological scans and histopathology of 2 patients with KCOTs that underwent malignant transformation into PIOSCC.

DISCUSSION

A comprehensive literature review was performed to similar reports documenting the malignant transformation of KCOTs. The potential for KCOTs to undergo malignant change should prompt oral maxillofacial surgeons and otolaryngologists to exercise a high index of suspicion when treating these lesions. Patients persisting with unresolved disease after treatment should be investigated for malignant transformation. Detailed histopathological examination of KCOT specimens is recommended to detect small foci of SCC which may be present in the epithelium.

Visual perception of multilocular radiolucent mandibular lesions quantified by morphometric analysis

OBJECTIVE

The aim of this study was to analyse the visual perceptions of different experts with respect to multilocular radiolucent lesions in circumstances when the diagnosis is either known or unknown.

METHODS

6 radiographs of ameloblastomas (AMELs), keratocystic odontogenic tumours (KOTs), central giant cell lesions (CGCLs) and myxomas (MIXs) were analysed by 16 dental experts [stomatologists/oral surgeons (SS) and dental radiologists (R)]. They delimited the lesions prior to having knowledge of the diagnosis (T1) and after 30 days, when they were aware of the histopathological results (T2). For each image, the following morphometric parameters were calculated: area (A), perimeter (P) and shape factor (SF); after image subtraction procedures (T1 - T2), the exclusive area (EA) of the non-overlapping delimited region was also calculated.

RESULTS

For both groups, the T2 area was larger than the T1, although the EA of the SS group was higher than that of the R group independently of the type of lesion. The SF from the SS group was greater than that from the R group, and at T2 the SF values were higher for both groups. AMELs and MIXs showed larger SF and A values; the SS group tended to have the greatest changes in the delimitations of the lesions at T2.

CONCLUSIONS

The methodology allowed us to quantify differences in the spatial perceptions of professionals. The knowledge of the diagnosis and the expertise of examiners influenced the examiner's perception of the limits of the lesions independently of the actual biological behaviour of the lesion.

There is little evidence that other clinical and conventional radiographic features are better than minimal buccolingual expansion for the diagnosis of nonsyndromic keratocystic odontogenic tumor

PURPOSE/QUESTION

To determine if there are other clinical or conventional radiographic signs available to improve the diagnosis of keratocystic odontogenic tumors compared with using minimal or no buccolingual expansion alone.

SOURCE OF FUNDING

Information not available.

TYPE OF STUDY/DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 3: Other evidence.

STRENGTH OF RECOMMENDATION GRADE

Grade C: Consensus, disease-oriented evidence, usual practice, expert opinion, or case series for studies of diagnosis, treatment, prevention, or screening.

Two-stage treatment protocol of keratocystic odontogenic tumour in young patients with Gorlin-Goltz syndrome: marsupialization and later enucleation with peripheral ostectomy. A 5-year-follow-up experience

OBJECTIVE

Keratocystic odontogenic tumour (KCOT) is a benign uni- or multicystic intraosseous odontogenic tumour with potential for local destruction and tendency for multiplicity, especially when associated with Gorlin-Goltz syndrome. We suggest a conservative surgical treatment based on marsupialization and later enucleation with peripheral ostectomy in order to preserve jaw's integrity in young patients.

METHODS

Three young patients affected of nevoid basal cell carcinoma syndrome (NBCCS or Gorlin-Goltz syndrome) presented large and multiple KCOTs, which have been treated following a two-stage surgical strategy. Initially marsupialization was performed and after a mean period of 10 months, contextually to evident reduction in radiological size image, enucleation with peripheral ostectomy was carried out.

RESULTS

All the patients showed high collaboration in daily self-irrigation of the stomia with chlorhexidine 0.2% during the period of marsupialization. Definitive surgical intervention led to complete healing and no signs of recurrence have been observed during a 5-year-follow-up.

CONCLUSIONS

The main advantage of this modality is the preservation of important anatomical structures involved in the lesion and jaw's continuity. Therefore in a selected group of cooperative patients, especially those affected of Gorlin-Goltz syndrome, the surgical protocol exposed allows for a less invasive approach with excellent results avoiding extensive disfiguring procedures.

Keratocystic odontogenic tumour: systematic review

OBJECTIVES

The aim of this review is to evaluate the principal clinical and conventional radiographic features of non-syndromic keratocystic odontogenic tumour (KCOT) by systematic review (SR), and to compare the frequencies between four global groups.

METHODS

The databases searched were the PubMed interface of Medline and LILACS. Only those reports of KCOTs that occurred in a series of consecutive cases, in the reporting authors' caseload, were considered.

RESULTS

51 reports, of 49 series of cases, were included in the SR. 11 SR-included series were in languages other than English. KCOTs affected males more frequently and were three times more prevalent in the mandible. Although the mean age at first presentation was 37 years, the largest proportion of cases first presented in the third decade. The main symptom was swelling. Over a third were found incidentally. Nearly two-thirds displayed buccolingual expansion. Over a quarter of cases recurred. Only a quarter of all SR-included reported series of cases included details of at least one radiological feature. The East Asian global group presented significantly as well-defined, even corticated, multilocular radiolucencies with buccolingual expansion. The KCOTs affecting the Western global group significantly displayed an association with unerupted teeth.

CONCLUSIONS

Long-term follow-up of large series that would have revealed detailed radiographic description and long-term outcomes of non-syndromic KCOT was lacking.

Cystic lesions of the jaws in edentulous patients: analysis of 27 cases

In this retrospective study we reviewed the distribution, characteristics, and treatment of 27 cystic jaw lesions in edentulous patients, and compared these with 242 cysts in dentate patients. The mean age was 60 years (range 46-74), and the male:female ratio 4.4:1. The maxilla was more affected than the mandible, with radicular/residual cysts being the most common. Patients were treated by marsupialisation, enucleation, or enucleation with bone grafting. Edentulous men were at higher risk than women of developing cystic lesions in the maxilla. Patients who are edentulous alert us to the possibility that their general health may be compromised, and this should be kept in mind when planning treatment.

Characterization and management of the keratocystic odontogenic tumor in relation to its histopathological and biological features

Keratocystic odontogenic tumor (KCOT), formerly referred to as odontogenic keratocyst, is a benign neoplasm of odontogenic origin which may present an aggressive and infiltrative behavior leading to high recurrence rates. A review of the various treatment modalities, ranging from simple enucleation to radical surgery is portrayed in relation to clinical, radiological, histopathological and molecular features. Although prognostic factors based on clinico-pathologic and immunohistochemical findings for determining the potential for recurrence of KCOT still remains unclear, its use for determining the potential for recurrence of KCOT after surgical treatment may become important to successfully manage this neoplasm's aggressive behavior. The key element for future management of KCOTs will probably be based on thorough knowledge of the biological basis of this tumor, thereby enabling a more tailored treatment approach.

[Skin and teeth]

Skin and teeth not only share several characteristics in their development but also have a similar ontogenetic origin from the ectoderm. Thus, numerous congenital diseases, such as genetic, infectious, inflammatory, and immune disorders affect both skin and teeth. Particularly skin diseases are often identified by the synopsis of systemic symptoms. The understanding and appreciation of dental abnormalities guides dermatologists in the diagnosis and identification of syndromes as well as in finding an optimal therapy.

Keratocystic odontogenic tumor: a review

The odontogenic keratocyst is a very well known odontogenic cyst. There are many types of cysts of the jaws, but what makes the odontogenic keratocyst unusual are its characteristic histopathological and clinical features, including potentially aggressive behaviour, high recurrence rate, and an association with the nevoid basal cell carcinoma syndrome. The characteristic histologic feature i.e. the presence of parakeratin, is unique amongst all the different inflammatory and developmental cysts that occur in the jaws. Many treatment modalities have been advocated for its treatment, but none in particular has been regarded as the best treatment option. The 2005 WHO classification now uses the term 'keratocystic odontogenic tumor'. We present a review of treatment modalities of the KCOT.

Keratocystic odontogenic tumor invading the right maxillary sinus: a case report

Keratocystic odontogenic tumor (KCOT) is a benign intraosseous neoplasm of the jaw. Involvement of the maxillary sinus is an unusual presentation. We present the case of a 23-year-old man with extensive KCOT and impacted third molar in the right maxillary sinus. The clinical, radiological, and histological features of this tumor and its surgical management are discussed.

Nevoid basal cell carcinoma syndrome (Gorlin syndrome)

Nevoid basal cell carcinoma syndrome (NBCCS), also known as Gorlin syndrome, is a hereditary condition characterized by a wide range of developmental abnormalities and a predisposition to neoplasms.

The estimated prevalence varies from 1/57,000 to 1/256,000, with a male-to-female ratio of 1:1.

Main clinical manifestations include multiple basal cell carcinomas (BCCs), odontogenic keratocysts of the jaws, hyperkeratosis of palms and soles, skeletal abnormalities, intracranial ectopic calcifications, and facial dysmorphism (macrocephaly, cleft lip/palate and severe eye anomalies). Intellectual deficit is present in up to 5% of cases. BCCs (varying clinically from flesh-colored papules to ulcerating plaques and in diameter from 1 to 10 mm) are most commonly located on the face, back and chest. The number of BBCs varies from a few to several thousand. Recurrent jaw cysts occur in 90% of patients. Skeletal abnormalities (affecting the shape of the ribs, vertebral column bones, and the skull) are frequent. Ocular, genitourinary and cardiovascular disorders may occur. About 5–10% of NBCCS patients develop the brain malignancy medulloblastoma, which may be a potential cause of early death.

NBCCS is caused by mutations in the PTCH1 gene and is transmitted as an autosomal dominant trait with complete penetrance and variable expressivity.

Clinical diagnosis relies on specific criteria. Gene mutation analysis confirms the diagnosis. Genetic counseling is mandatory. Antenatal diagnosis is feasible by means of ultrasound scans and analysis of DNA extracted from fetal cells (obtained by amniocentesis or chorionic villus sampling). Main differential diagnoses include Bazex syndrome, trichoepithelioma papulosum multiplex and Torre's syndrome (Muir-Torre's syndrome).

Management requires a multidisciplinary approach. Keratocysts are treated by surgical removal. Surgery for BBCs is indicated when the number of lesions is limited; other treatments include laser ablation, photodynamic therapy and topical chemotherapy. Radiotherapy should be avoided. Vitamin A analogs may play a preventive role against development of new BCCs.

Life expectancy in NBCCS is not significantly altered but morbidity from complications can be substantial. Regular follow-up by a multi-specialist team (dermatologist, neurologist and odontologist) should be offered. Patients with NBCCS should strictly avoid an excessive sun exposure.

Odontogenic Keratocyst of mandible

The Odontogenic Keratocyst is a developmental odontogenic cyst and deserves special attention because of its peculiar histopathologic features and biologic behavior. It is believed that the Odontogenic Keratocyst arises from the proliferation of remnants of dental lamina. It is usually asymptomatic, and solitary lesion, however, it may be associated with Nevoid Basal Cell Carcinoma Syndrome. This work aimed to present a case of a very extensive Odontogenic Keratocyst in a 28-year-old woman.

A review of odontogenic keratocysts and the behavior of recurrences

OBJECTIVE

The purpose of this study is to report experiences of odontogenic keratocysts (OKCs) and analyze information regarding recurrences to better understand the nature of recurrences.

STUDY DESIGN

Fifty-one cases of OKC treated at the Faculty of Dentistry, Chulalongkorn University, from 1988 to 2003 were studied retrospectively. Clinicoradiographic features, histologic features, and methods of treatment were reviewed. Recurrences were analyzed and compared with respect to sites of involvement, relationship to the remaining teeth, and methods of treatment.

RESULTS

OKCs occurred predominantly in the 11- to 40-year-old age group. The body-angle-ramus area of mandible was the most common site of occurrence. Radiographically, the unilocular to multilocular radiolucency ratio was 2.5:1. Multilocular lesions occurred more frequently in the mandible (P < .05). Most of the lesions were diagnosed histologically as parakeratinized OKC (93.7%). The patients were followed from 1-14.6 years. However, 20 patients were lost to follow-up after a short period of time, and recurrences were found in 7 out of 31 cases (22.6%). The recurrent tumors occurred more frequently in patients who had an OKC associated with the remaining teeth and were treated by enucleation or enucleation with adjuvant therapy.

CONCLUSIONS

According to a high recurrent rate of OKCs treated by enucleation, clinicians should give more attention to the dentate area if the enucleation is chosen as the treatment of choice.

Molecular evidence supporting the neoplastic nature of odontogenic keratocyst: a laser capture microdissection study of 15 cases

AIMS

The bland histology of odontogenic keratocyst (OKC) belies its capacity for aggressive behaviour. Genetic alterations of OKC have not been well studied. We examined the frequency and pattern of allelic imbalance on five different chromosome regions from 15 patients with OKC.

METHODS AND RESULTS

Laser-assisted microdissection was performed on formalin-fixed paraffin-embedded tissue. Polymerase chain reaction analysis of extracted DNA targeted five polymorphic DNA markers (D3S1285, D9S161, D11S1316, D13S290, and TP53) representing chromosome regions 3p14, 9p21, 11q23, 13q12.1 and 17p13, respectively. All 15 cases of OKC were informative at a minimum of three of five loci, with 11 informative on all five loci. Twelve of 15 cases (80%) demonstrated loss of heterozygosity (LOH). Seven cases (47%) showed LOH at more than two DNA loci. The frequency of LOH was 5/11 (45%) at D3S1285, 3/15 (20%) at D9S161, 4/14 (29%) at D11S1316, 8/14 (57%) at D13S290 and 3/15 (20%) at TP53.

CONCLUSIONS

The majority of OKCs harbour chromosomal abnormalities. This finding supports the supposition that OKCs are neoplastic. Furthermore, OKCs harbour allelic loss at some of the same loci identified in squamous cell carcinoma. This may aid in explaining the rare occurrence of squamous cell carcinoma arising in OKC.

Immunohistochemical Evaluation of VEGF Inflamed Cystic Radicular Lesions and in Keratocysts

Vascular Endothelial Growth Factor, also known as Vascular Permeability Factor, is a multifunctional cytokine hyperexpressed during angiogenesis and in numerous physiological and pathological processes characterised by an increase of vascular permeability. The aim of this study was to evaluate the angiogenetic processes which are accompanied by an expansion of cystic radicular lesions and of keratocysts of the jaw bone. 12 subjects were chosen with an average age of 43 years, of whom 8 were males and 4 females. After an accurate history and physical examination, the patients underwent surgery for removal of the cysts. The samples taken were histologically and immunohistochemical examined. The histological exam confirmed the diagnosis of radicular cysts and keratocysts. The immunohistochemical examinations were positive for VEGF in all the lesions analysed, even though they had different immunostaining. Using a semi-quantitative method, in the radicular cyst samples it was possible to highlight a wider expression of the vascular component, both in the inflamed area and the adjacent stroma. The lesions with keratin content showed newly formed and modest vascularisation both in the area showing slight inflammation, where the cellular component was prevalent, and in the adjacent areas showing no inflammation. Therefore, angiogenesis could take on a primary role in the development of cystic lesions of the jaw. However, the differences of expression of the VEGF protein suggest the need for wider monitoring to better evaluate a possible use of such a protein as a diagnostic marker.

A Retrospective Review of Treatment of the Odontogenic Keratocyst

PURPOSE

The purpose of this study was to evaluate different surgical treatment methods for odontogenic keratocysts and the outcome of those treatments over a 25-year period.

PATIENTS AND METHODS

A retrospective review was performed of 40 patient charts treated at the University of Iowa Hospitals and Clinics (Iowa City, IA) from 1977 to 2002 with the diagnosis of odontogenic keratocyst. Demographic data were collected along with lesion location, symptoms present at initial presentation, surgical treatment rendered, length of follow-up, and incidence of recurrence.

RESULTS

Surgical treatments included enucleation, enucleation with Carnoy's solution, peripheral ostectomy, peripheral ostectomy with Carnoy's solution, and en bloc resection. Recurrence was found in 9 to 40 patients. Seven of 9 recurrences (78%) occurred in 5 years or less, with 2 (22%) occurring more than 5 years after initial treatment. Patients treated with enucleation had a recurrence rate of 54.5% (6 of 11 patients). One of 2 patients treated with enucleation and Carnoy's solution had a recurrence. Those treated with peripheral ostectomy had a recurrence rate of 18.2% (2 of 11). Peripheral ostectomy with Carnoy's solution had no recurrences (0/13).

CONCLUSION

Treatment of an odontogenic keratocyst with peripheral ostectomy, with or without the use of Carnoy's solution, had a significantly lower rate of recurrence. Treatment with enucleation, with or without the use of Carnoy's solution was associated with a significantly higher recurrence rate.

Molecular Analysis to Demonstrate That Odontogenic Keratocysts Are Neoplastic

Context.—Odontogenic keratocysts (OKCs) are unique odontogenic lesions that have the potential to behave aggressively, that can recur, and that can be associated with the nevoid basal cell carcinoma syndrome. Whether they are developmental or neoplastic continues to be debated.

Objectives.—To identify loss of heterozygosity of tumor suppressor genes in OKCs and to suggest a pathogenetic origin for these lesions.

Design.—We examined 10 OKCs for loss of heterozygosity of tumor suppressor genes, using a microdissection and semiquantitative genotyping analysis. The genes analyzed included 10 common tumor suppressor genes, as well as the PTCH gene, which is mutated in nevoid basal cell carcinoma syndrome.

Results.—Loss of heterozygosity was seen in 7 of 10 cases, with a frequency between 11% and 80% of the genes studied. The genes that exhibited the most frequent allelic losses were p16, p53, PTCH, and MCC (75%, 66%, 60%, and 60%, respectively). Daughter cysts were associated with a higher frequency of allelic loss (P = .02), but epithelial budding was not.

Conclusions.—Our study indicates that a significant number of OKCs show clonal loss of heterozygosity of common tumor suppressor genes. The finding of clonal deletion mutations of genomic DNA in these cysts supports the hypothesis that they are neoplastic rather than developmental in origin.

Odontogenic cysts, odontogenic tumors, fibroosseous, and giant cell lesions of the jaws

Odontogenic cysts that can be problematic because of recurrence and/or aggressive growth include odontogenic keratocyst (OKC), calcifying odontogenic cyst, and the recently described glandular odontogenic cyst. The OKC has significant growth capacity and recurrence potential and is occasionally indicative of the nevoid basal cell carcinoma syndrome. There is also an orthokeratinized variant, the orthokeratinized odontogenic cyst, which is less aggressive and is not syndrome associated. Ghost cell keratinization, which typifies the calcifying odontogenic cyst, can be seen in solid lesions that have now been designated odontogenic ghost cell tumor. The glandular odontogenic cyst contains mucous cells and ductlike structures that may mimic central mucoepidermoid carcinoma. Several odontogenic tumors may provide diagnostic challenges, particularly the cystic ameloblastoma. Identification of this frequently underdiagnosed cystic tumor often comes after one or more recurrences and a destructive course. Other difficult lesions include malignant ameloblastomas, calcifying epithelial odontogenic tumor, squamous odontogenic tumor, and clear-cell odontogenic tumor. Histologic identification of myxofibrous lesions of the jaws (odontogenic myxoma, odontogenic fibroma, desmoplastic fibroma) is necessary to avoid the diagnostic pitfall of overdiagnosis of similar-appearing follicular sacs and dental pulps. Fibroosseous lesions of the jaws show considerable microscopic overlap and include fibrous dysplasia, ossifying fibroma, periapical cementoosseous dysplasia, and low-grade chronic osteomyelitis. The term fibrous dysplasia is probably overused in general practice and should be reserved for the rare lesion that presents as a large, expansile, diffuse opacity of children and young adults. The need to use clinicopathologic correlation in assessing these lesions is of particular importance. Central giant cell granuloma is a relatively common jaw lesion of young adults that has an unpredictable behavior. Microscopic diagnosis is relatively straightforward; however, this lesion continues to be somewhat controversial because of its disputed classification (reactive versus neoplastic) and because of its management (surgical versus. medical). Its relationship to giant cell tumor of long bone remains undetermined.