The Study Of Radiological Features Of Multiple Primary Keratocystic Odontogenic Tumor(MPKCOT) In Jaw Bones

BackgroundKeratocystic odontogenic tumor(KCOT) is a benign uniloculus or multiloculus odontogenic tumor. It frequently occurs in manidbular molar region and mandiular ramus, and it possibly happens in any region which is associated with the development of tooh. KCOT presents relatively higher reproduction potentiality and special growth pattern. Its characteristic lining with parakeratinized stratified squamous epithelium maybe cancerization. It also associated with nevoid basal cell nevus syndrome and easily recurs after conservative operations. KCOT's original name is odontogenic keratocyst (OKC). AHLFORS et al research results show that increases of Mitogenic index of keratocyst looks similar to that of ameloblastoma, and then they think Keratocyst is a benign tumor. STENMEN et al compared keratorcyst and ameloblastoma through cell culture, and found that epithelial cell of keratocyst remains metabolism in the nutrient medium and this is very resemble to ameloblastoma. In result, they think keratocyst also has the characteristic of tumors.WANG En-bo et al research results show Keratocyst has relative higher epitheliosis ability and present more positive cells of proliferating cell nuclear antigen (PCNA). Through study cell proliferation dynamics by measuring the quantity of PCNA positive cells and DNA content, they found that the Proliferative activity of epithelial cell of Keratocyst looks similar to that of ameloblastoma. Epitheliosis is the basic characteristic of Epithelial tumor and odontogenic keratocyst also has this basic characteristic. So, odontogenic keratocyst is regarded as a benign tumor with invasive growth. Its invasive growth resemble to that of mural ameloblastoma. Based on this, odontogenic keratocyst (OKC) is suggested to be changed to keratocystic odontogenic tumor. In the WHO new classification of head and neck tumor in 2005, odontogenic keratocyst (OKC) is classified in odontogenic benign tumor and named it as keratocystic odontogenic tumor (KCOT).The most frequent occurrence age range of keratocystic odontogenic tumor (KCOT) is 10-29 years old and BROWNE reported that 40-50 years old is the second. Male is more than female. KCOT's clinical features is enlargement of jaw and ache after secondary infection. Due to its concealed growth, it is difficult to be diagnosed earlier except it caused enlargement of jaw or other symptom. The growth of KCOT has no self-limitation and this leads to serious destruction of jaw. The chances of recurrence are relatively higher after operations and it is maybe associated with the biological behavior of the lining with epithelial cell stratum. Study shows the ability of mitochysis of epithelial cell stratum of KCOT and its marker of cell proliferation increased, and this proves that KCOT has the proliferative ability of tumor cell.Multiple primary keratocystic odontogenic tumor(MPKCOT) means the host has two or more primary keratocystic odontogenic tumor at the same time or in line. Cystic tumors can be classified synchronous cystic tumor and asynchronous tcystic tumore by the appearance interval. The interval for the former is less than 6 six months and the latter is more than that. For example, MPKCOT, is reported in many pape, is Nevoid basal cell carcinoma syndrome containing multiple primary cystic tumor. Many basic researches are being done for keratocystic odontogenic tumor, specially in the Gene field. Therapy methods of KOCT have been improved but analysis of radiological features is incomprehensive. Diagnosis of early primary lesions of MPKCOT is never seen in any literature. Primary lesions of Asynchronous Multiple primary keratocystic is easily be diagnosed as recurrence by mistake. The statistical odds of the recurrence rate about Keratocystic odontogenic tumor is 22%-60%. There are five main factors leads to high recurrence:first of all, Cyst wall is very thin and crisp, and this makes it very hard to completely remove KCOT by surgery when bones are destructed. Secondly, epithelial cell with lining has higher dissociative ability. Thirdly, Inner or outside epithelial islands t of cyst wall and ascus may remnant. Fourth, Primary lesions of Asynchronous multiple primary keratocystic was easily regarded as recurrence lesions. Fifth, less advanced examining facilities made KCOT earlier minor primary lesions missed diagnosis, however return checkup regard it as recurrence lesions.To better collect statistic and better summarize its radiological features, this paper name it as MPKCOT the first time, and it is helpful to diagnose the earlier minor primary lesions of MPKCOT, threrapy it and provide theoretical instructions for prognosis.Basal cell nevus syndrome(BCNS), also known as jaw cysts-naevoid basal cell epithelioma-bifid rib asyndrome or Gorlin's syndrome. It is an inherited autosomal dominant disorder with complete penetrance and extreme variable expressivity. In a population, the prevalence is 1 per 57,000 people, with a 3:1 male/female gender predilection. It is characterized by main features, including multiple basal cell nevoid, jaw cysts, congenital skeletal anomalies, central nervous system abnormalities, intracranial ectopic calcification, palmar and plantar pits and specifical physiognomy etc. Moreover, this syndrome is characterized by up to 100 less common features, including associated endocrinopathies, potential for mental retardation, medulloblastoma, ovarian fibromas, and an increased incidence of cleft lip and/or palate. Multiple cystic tumor of jaw is one of the characters of BCNS, and 65%-90 % of BCNS have multiple cystic tumor of jaw. Generally speaking, patient with three or more aboved main features can be diagnosed as BCNS.I studied one BCNS patient for a long term and found that its multiple cystic tumor showed some special images features such as asynchronism and symmetry. It means MPKCOT Radiologic features maybe have regularity. To investigate the common radiologic features of multiple primary cystic lesions and provide supportive theory for diagnosis of earlier minor primary lesions, it summed up the no. of cysts, location of lesion, sick time, radiologic features, connection between MPKCOT and BCNS in 15 diagnosed cases in this paper.Objective1. To reveal the occurrence regularity of multi primary keratocystic odontogenic tumor by investiging and analyzing the radilogic features on panormagram and Cone bean-CT images, and will be made to theory support to diagonose earlier minor primary cystic tumor lesions.2. To explore the diagnostic value of Cone-bean CT in diagnosis of earlier minor primary keratocystic odontogenic tumor.Materials and Methods1. Study cases selects20 cases were collected from July,1997 to Feb.2010 by Guangdong Provincial Stamatological Hospital. Among them,5 cases are not included into study due to imcomplete radiologic data. The remaining 15 cases were analyzed and investigated respectively as all these cases have a complete set of radiologic data including panoramagram, posteroanterior radiograph of skull, lateral radiograph of skull or Cone-bean CT, Chest radiograph, detailed hospital medical records and histopathology etc.2. Radiologic analysisClassified and analyzed the radiologic features of all the original radiologic data and return-visit exam of 9 cases. All these radiologic features includes position constancy of lesion, relation between lesion and the location of the tooth, appearce regularity of original lesion, connection between MPKCOT and BCNS etc.6 subsequent MPKCOT cases are given comprehensive diagnosis with radiologic regularity revealed by above study and doubtful minor lesions are screened Cone-bean CT.Results1,New radiologic features of MPKCOT:①.Lesions Symmetry:Occurance of MPKCOT is dominated by Gene. Maxillary and mandibular develope from amalgamation of two bones. Lesions are usually detected in both Bilateral maxillary and bilateral mandibular at the same time and it shows symmetry feature. Human body is controlled by many regulatory systems and this made some of lesion are suspended and did not show. Although few cases did show symmetry, it is very obvious that MPKCOT are symmetric.②. Lesions Position Constancy:the position of primary lesions are found in 87 (?)78,87(?)78,543(?)345,543(?)345 area.③. Asynchronism feature:although MPKCOT is dominated by Gene, it is regulated by many regulatory systems at the same time and this makes occurrance of lesions deferred. Radiologic feature of Asynchronism accord with Knudson's two-hit model, namely the first hit is the existence of dominant gene and the seond hit is diverse influence aspects including radiation such as X-rays or actinicity etc. Two-hit model could explain symmetrical and constant multi primary lesion very well. Dominant gene activating all target organs (synchronism) or partial target organs (aynchronism) in a particular location. Stimulating inactive target organs and lead to the late multi lesionsoccurrance in succession are the second hit.④.High rate of containg teeth:77 cystic lesion were found in 15 cases, average 5.1 per person.41 lesions containing teeth occupy 53.2% of all these lesions.2 Correlation between basal cell nevoid syndrome (BCNS) and MPKCOTEach MPKCOT in 15 cases has three or more than three main features of BCNS and this means MPKCOT had a high correlation with BCNS-most possibly all the MPKCOT are BCNS, however, not all BCNS have multiple primary cystic lesions of jaws. So, whether all BCNS are MPKCOT, this needs to be proved by a mass of cases, that's having disease of MPKCOT can be diagonised as BCNS needs to be proved by a mass of cases insteading of having three or more than three above radiologic features can be diagonosed as BCNS.3. The value of Cone-bean CT in diagonosis of earlier minor primary cystic tumor lesion.Cone-bean CT can detect even 2mm earlier minor primary lesion and this offsets the defects of panoramagram:①. The width of focal trough of Panoramagram machine is about 2 mm (front teeth region)-4 mm (molar region). If the position of lesions does not fall in the width of focal trough, then early lesions will become very blurred or will not be detected.②. Panoramagram radiography is a 2 dimension image of 2-4mm overlapped jaw bones, early lesions with diameters less than 2-4mm only be showed as the slightly uneven decreased bone density on 2 dimension image.③. When diameter of early lesions is more than 2-4mm and the pafocal trough of panoramagram machine does not pass the lesion center, the images also shows decreased bone density. Above mentioned three points caused missing diagnosis of many early lesions.Early minor Cystic lesion is completely located the cancellous jaw bones and the growth resistance is even. It presents a smooth round or oval shape uniform radiolucency lesion in high resolution Cone-bean CT images. The section of high resolution Cone-bean CT images can reach 100μm, it can completely overcome the defects of no presence of being overlapped images. Early KCOT lesions demonstrate a smooth round or oval shape uniform radiolucency lesion with well-defined border in Cone-bean CT.With above mentioned MPKCOT's radiologic features and its lesions occurrence regularity, screening exams to the specific doubtful images in panoramagram are done by Cone-bean CT and found 13 earlier minor primary lesions in 6 cases of MPKCOT.Conclusions1. MPKCOT presented special image features of asynchronism, symmetry and position constancy. Basing on the features mentioned above, the minor primary lesion of MPKCOT in other regions can be diagnosed earlier.2. BCNS with MPKCOT also have aboved mentioned radiological features. One view point will be proved in future that all the NPKCOT probably are BCNS.3. High resolution Cone-bean CT has a great value in diagonosis of the minor primary cystic tumor lesion and the minor primary lesion can be diagnosed earlier.