odontogenic cysts of the jaw are lesions lined by epithelium of odontogenic origin that 
 contain liquid or semi - solid material in their interior . radiologically they are 
 characterized by a homogeneous radiolucent image , usually round or ovoid and well 
 delineated by sclerotic margins . despite having peculiar clinical and radiographic characteristics , the differential 
 diagnosis of odontogenic cysts and tumors can be challenging for dental physicians , 
 radiologists and surgeons , and it is of great importance for a definitive diagnosis 
 establishment and treatment planning . in the latest world health organization 
 ( who ) classification , some 
 lesions previously considered as cystic are now classified as cystic tumors , once the 
 growth mechanism does not occur due to a difference in pressure , but rather for other 
 reasons , such as epithelium activity proliferation . this is the case of the keratocystic 
 odontogenic tumor ( kot ) , formerly known as odontogenic keratocyst . epithelial lining 
 proliferation of kot has a higher rate than non - odontogenic and radicular cysts , and is 
 similar to the one found in ameloblastoma and the dental lamina . immunohistochemical staining for ki-67 
 proliferation antigen shows numerous cells in cycle , not only in the basal , but also in 
 the suprabasal epithelial kot regions . this change in denomination made by who reflects the neoplastic nature of the lesion , 
 due to its aggressive potential , infiltrating behavior through the medullar cavity of 
 jaw , high recurrence rates and association with the nevoid basal cell carcinoma 
 syndrome . kot tends to grow occupying the anteroposterior medullar spaces , thus causing extensive 
 lesions with little or no bone expansion . it is more commonly located in the posterior 
 region of the mandible , presents scalloped radiographic margins , can displace teeth and 
 usually does not reabsorb roots . it 
 is worth emphasizing that , radiographically , kot may mimic a number of other odontogenic 
 jaw cysts , or even appear as a lesion with a multilocular aspect . it is important , then , 
 to include this tumor in the differential diagnosis of jaw radiolucent lesions , either 
 unilocular or multilocular . a suitable semiotechnique method to help determining the clinical and differential 
 diagnosis between jaw cystic and tumoral lesions is aspiration puncture . the aspiration 
 of a cystic lesion can provide additional information about its content ( if liquid or 
 serous , or if absent ) and aid in the presumptive clinical diagnosis at the moment of its 
 application . cell block is a 
 histological technique largely used in medical pathology for pleural fluid , peritoneal 
 fluid , bronchial washings , fine - needle aspirations , and other cytological 
 specimens . cell blocks prepared 
 from residual tissue fluids and fine - needle aspirations can be useful adjuncts to smears 
 for establishing a more definitive diagnosis . the great advantage of cell block elaboration is the decrease in 
 cellular dispersion - characteristic of tissue fluids - through centrifugation and its 
 embedment in paraffin , which allows a better analysis of the collected liquid content , 
 as well as the obtention of fine sections for analysis . nevertheless , due to the 
 fact that jaw cystic lesions are similar to cysts located elsewhere in the human body 
 and also have dispersed cells in a liquid content , it offers a timely and appropriate 
 application . the aim of this research was to evaluate the viability of cell block 
 technique as a complementary method for the presumptive diagnosis starting from the 
 collected material from lesions with clinical diagnosis of jaw cysts . the project that originated this study was approved by the research ethics committee of 
 the federal university of santa catarina ( ufsc ) , registration number 075/2006 . the sample was made up of 17 patients with cyst - like jaw lesions that had indication for 
 fine - needle aspiration biopsy , being assisted at the stomatology , oral and maxillofacial 
 traumatology clinics of the university hospital of federal university of santa catarina , 
 brazil . all participants were volunteers who were informed about the study purposes and 
 were asked to sign an informed consent form . submucous lesions were submitted to asepsis , local anesthesia , and puncture by an 18 g 
 ( gauge ) needle connected to a 10 ml syringe . the syringe containing the material 
 collected was immediately stored in a container with ice and put aside for laboratory 
 procedures . in the laboratory , the syringe material was transferred to a test tube and centrifuged 
 at 2,000 rpm for 20 min . the pellet obtained thereby was transferred onto absorbent 
 paper and fixed in a 10% formaldehyde solution for 24 h. after that , the material was 
 sequentially processed as follows : dehydration , clearing , impregnation by and embedment 
 in paraffin . five - micrometerthick sections were obtained and stained with hematoxylin 
 and eosin ( h&e ) . specimens were analyzed by light microscopy ( axiostar plus ; carl zeiss , oberkochen , 
 germany ) to characterize the type of material collected in relation to the presence of 
 epithelial cells , inflammatory cells , keratin , erythrocytes , or any other components 
 that could be present . all patients who participated in this study were submitted to appropriate radiographic 
 exams and incisional or excisional biopsy , in accordance with clinical indication . results from the 
 histological examination of the cell block were compared with the histopathological data 
 of the biopsy , as well with the clinical and radiographic data of the lesions . the 
 analysis of the clinical , radiographic and cell block data , combined with 
 histopathological examination of the biopsied tissue allowed determining the lesion 
 diagnosis . all patients were treated properly and were followed by clinical / radiographic 
 postoperative control . cell blocks of 17 cyst - like jaw lesions were performed . based on clinical and 
 radiographic images the 
 radiograph findings showed unilocular radiolucency lesions with well - defined sclerotic 
 margins ( figures 1a and b ) . in 9 cases ( 53% ) , cytological analysis revealed a large number 
 of erythrocytes , several inflammatory cells , and a small number of epithelial cells , 
 with cholesterol clefts in some cases ( figures 2a 
 and b ) . histopathological analysis associated with 
 clinical and radiographic characteristics rendered the diagnosis of inflammatory 
 odontogenic cysts : 3 residual cysts and 6 radicular cysts ( figures 2c and d ) . in 8 cases 
 ( 47% ) , diagnosed as kots by the histopathological analysis , the cell block method showed 
 a predominant occurrence of keratin and the presence of parakeratin in some areas ( figures 3a , b , 
 c and d ) . panoramic radiographs : a , classical cyst aspect as a unilocular radiolucency 
 lesion with well - defined sclerotic margins in a mandible residual cyst ; b , 
 maxillary keratocystic odontogenic tumor with unusual bone expansion and tooth 
 displacement a , cytological analysis ( cell block ) of an inflammatory cyst [ hematoxylin - eosin 
 ( h&e)100x ] ; b , high magnification showing cholesterol clefts and a large 
 number of erythrocytes ( h&e 400x ) ; c , histopathological analysis of the same 
 lesion showing a cystic capsule with epithelial lining ( h&e 100x ) ; d , high 
 magnification showing cholesterol clefts inside the capsule and the stratified 
 epithelial lining ( h&e 400x ) a , cytological analysis ( cell block ) of keratocystic odontogenic tumor showing 
 keratin [ hematoxylin - eosin ( h&e)100x ] and , b , parakeratin ( high magnification ) 
 ( h&e 1,000x ) ; c , histopathological analysis of the same lesion with a 
 conjunctive tissue capsule lined by thin and uniform epithelial tissue ( h&e 
 100x ) ; d , high magnification showing the stratified epithelial lining with a 
 palisade basal layer and corrugated parakeratin on the surface ( h&e 400x ) therefore , 
 establishing a correlation between clinical , radiographic , cytological , and 
 histopathological characteristics is essential for diagnosis and subsequently for the 
 best treatment planning for each specific case . jaw cysts and benign osseous tumors have a similar behavior in relation to evolution 
 period ( slow ) , expansion of the bone , eventual dental displacement , and even dental 
 resorption . in general , their 
 radiographic aspects can be confusing , and it is not always possible to make an accurate 
 clinical diagnosis among them . although the fine needle aspiration biopsy is a semiotechnique method frequently used to 
 analyze cyst - like lesion content , in most of the cases the collected material is 
 discarded . cell block is a histological technique that allows the microscopic analysis 
 of this material . the advantage of using the cell block technique is the decrease in 
 cellular dispersion , in an attempt to obtain maximum cellular concentration , which 
 facilitates microscopic analysis . another advantage is the fact that the material can be 
 stored for future use , if necessary , as in immunohistochemical essays . according to the studied cases , the cell block method proved to be very effective in 
 distinguishing kots from other lesions with similar clinical and radiographic aspects , 
 through parakeratin identification . the inflammation could affect the walls kot causing 
 epithelium metaplasia and loss of their peculiar characteristics7 . especially in cases 
 of incisional biopsy , the small selected area could indicate epithelial alterations and 
 cause difficulties in the histological diagnosis . in case of large lesions , the cell 
 block method also has the advantage of detecting the presence of parakeratin , as it was 
 observed in one of our cases , where the histopathological analysis showed a severely 
 inflamed area . some authors have report that keratocysts behave as benign neoplasm and should be 
 treated as such . however , kots tend 
 to grow , occupying the medullar cavity of bone without causing a significant expansion 
 and frequently reaching a considerable size , particularly in the mandible ramus and 
 angle . due to the fact that there is not enough information about the lesion development 
 period before its diagnosis , the recent classification of the odontogenic keratocyst as 
 a kot by who shows the importance of 
 establishing a correct diagnosis . kramer and toller ( 1973 ) mentioned 
 that the presence of keratin in the cystic content is a strong evidence that the lesion 
 is a kot . currently , it is known that parakeratin is the main substance found in this 
 lesion , and that orthokeratin focuses can also occur . cysts with a great amount of orthokeratin are called 
 orthokeratinized odontogenic cysts and have low aggressive potential and minimum 
 recurrence rate . this kind of cyst is 
 a rare lesion and , although the result of cell bock may be similar , they do not present 
 parakeratin , as in all kot cases of this study . a good exemplification of how cell block preparations can be very useful in the 
 differential diagnosis of cyst - like jaw lesions occurred in one of the reported cases of 
 kot ( figure 1b ) . this lesion had an unusual 
 behavior for a kot , causing bone expansion , dental displacement , and displacement of the 
 maxillary sinus floor , and it was clinically diagnosed as an infected radicular cyst . the clinical aspiration procedure showed a whitish and pasty material , compatible with 
 kot , and this clinical diagnosis was confirmed by the presence of parakeratin in the 
 cell block and later by its typical histopathological characteristics . it is also important to mention that some benign tumors may present a cystic 
 degeneration , such as ameloblastoma , ameloblastic fibroma and odontogenic adenomatoid 
 tumor , and consequently , 
 liquid content in their interior . the cell block method is a simple , fast and low - cost technique that can be used as an 
 adjunctive technique in the presumptive diagnosis of jaw cystic lesions . embedded cell 
 preparations by the cell block technique from fine needle aspiration biopsy are useful 
 for establishing a differential diagnosis between kot and jaw lesions with cystic 
 aspects , aiding the therapeutic planning of these lesions .
objectiveto evaluate the applicability of the cell block technique as a complementary 
 method for presumptive diagnosis in the analysis of cyst - like aspirates from jaw 
 lesions prior to histopathological diagnosis.material and methodsthe sample was made up of 17 cyst - like jaw lesions . 
 after puncture , the aspirates 
 were centrifuged , fixed in formalin , embedded in paraffin and processed . 
 all 
 lesions were biopsied and submitted to histopathological examination.resultsin 9 cases , the cytopathological analysis using the cell block method showed a 
 predominant presence of erythrocytes , inflammatory cells and few epithelial cells . 
 in the other 8 cases , 
 the cell block technique demonstrated the presence of 
 parakeratin , whose histopathological analysis confirmed the occurrence of 
 keratocystic odontogenic tumors ( kots).conclusionsaccording to the studied cases , the cell block method was proven to be a simple , 
 fast and low - cost technique to effectively differentiate kots from other lesions 
 with similar clinical and radiographic features . 
 the cell block technique 
 comprises cellular preparations useful to determine a clinical diagnosis and help 
 to develop a therapeutic plan for those lesions .