odontogenic cysts are classifed by the world health organization as infammatory and 
 developmental according to their epithelial lining .
lateral periodontal cysts ( lpc ) 
 have been regarded as an independent condition [ 1 - 4 ] .
lpcs are defined as nonkeratinized and noninflammatory developmental cysts located 
 adjacent or lateral to the root of a vital tooth .
this cyst 's most frequent location 
 is at the level of mandibular premolars but it has been reported occurring in the 
 other areas .
lpc is one of the cysts of lower incidence among developmental odontogenic cysts . 
 since pain or other clinical symptoms
have seldom been reported , the lesion is often 
 discovered on routine radiographic examination .
radiographs of the lateral 
 periodontal cyst show a well - circumscribed round or ovoid radiolucent area , usually 
 with a sclerotic margin .
most of them are less than 1 cm in diameter [ 5 - 8 ] .
histologically , the lateral periodontal cyst is a distinct type of developmental cyst 
 characterized by a thin , nonkeratinized epithelium usually 1 to 5 cell layers thick , 
 which resembles the reduced enamel epithelium .
the epithelial lining exhibits focal 
 thickenings or plaques , in which clear glycogen - containing epithelial cells have 
 often been found .
it presents unique characteristics and there is an important differential diagnosis 
 with lesions of endodontic and periodontal origin , and other cysts from the same 
 group [ 5 - 8 ] .
the pathogenesis of lpc , the gingival cyst of the adult , the 
 botryoid odontogenic cyst and the glandular odontogenic cyst may be correlated 
 .
some authors , based on the clinical 
 and morphological similarities , reinforce that the gingival cyst of the adult and 
 lpc present a common histogenesis , and these lesions may have the same extra - osseous 
 and intra - osseous characteristics , respectively .
this paper reports a classic case of lpc which is located in the anterior region of 
 mandible , and also presents a brief literature review of the clinical , radiological 
 and histopathological features of lpc .
a 50 year old black female patient was referred to so paulo state university 
 - unesp , so jos dos campos dental school , department of biosciences and 
 oral diagnosis , so jos dos campos , so paulo , brazil , complaining of 
 mandibular left lateral incisor mobility .
the patient reported that she had used the 
 stick to tooth in this region , shortly before the change was observed , approximately 
 six months ago .
the 
 palpation of vestibular surface of the alveolar process in the region of teeth # 32 
 and # 33 was asymptomatic .
radiographic examination revealed a 
 well - circumscribed , unilocular , radiolucent area with approximately 0.5 cm in 
 diameter adjacent to the roots of the left mandibular lateral incisor and canine 
 ( figure 1 ) .
periapical radiograph showing circumscribed radiolucent area located between 
 two vital teeth # 32 and # 33 . on the basis of these findings ,
a total enucleation 
 of the lesion was realized using a surgical curette ( figure 2 ) .
histological sections showed a single cavity 
 lesion lined by epithelium of variable thickness , sometimes displaying one or two 
 layers of cuboid cells and sometimes showing areas that formed thick clusters of 
 cells more voluminous in the midst of which several pas positive clear cells were 
 observed .
the capsule consisted of fibrous tissue with several bleeding areas and 
 absence of inflammation ( figure 3 b , c and 
 d ) .
the histological findings supported the diagnosis of lateral periodontal 
 cyst of developmental origin . a = photograph showing macroscopic aspects of the lesion .
b = histopathologic view of the lesion shows one cystic cavity only ; the 
 capsule of fibrous tissue showed several bleeding areas and absence of 
 inflammation ( hematoxylin and eosin stain , original magnification x25 ) .
c = histopathologic view of the lesion shows epithelium lining rich in cells 
 with glycogen ( hematoxylin and eosin stain , original magnification 
 x100 ) .
d = histopathologic view of the lesion shows pas positive clear cells ( pas 
 x100 ) .
follow - up of the case , twenty four months after operation , showed uneventful healing 
 and spontaneous regeneration of bone in periapical radiography .
lpc is considered as developmental odontogenic cyst with unusual occurrence that may 
 be associated with vital teeth .
literature review shows that the lpc is more prevalent in 
 adults in the 5th - 7th decades , with mean age of 52 years , without preference for 
 race or sex .
the most frequently reported location of lpc is the mandibular premolar 
 area , followed by the anterior region of maxilla ( table 1 ) [ 5,6,8,11 - 20 ] . in most cases 

the lpc does not present distinctive clinical symptoms ; the associated teeth are 
 vital , unless secondarily infected .
data from clinicopathological studies of lateral periodontal cyst 
 ( lpc ) the pathogenesis of lpc may be related to the three etiopathological hypotheses : 
 reduced enamel epithelium , remnants of 
 dental lamina   and cellular remnants of 
 malassez .
the first hypothesis is that the 
 cyst is lined by nonkeratinized epithelium reminiscent of the reduced enamel 
 epithelium which is supported by pcna immunohistochemical expression .
the second 
 theory is related to dental lamina remnants , based on the fact that lpc 
 histopathologically presents glycogen - rich clear cells , which is also seen in the 
 dental lamina .
the third hypothesis offered that the epithelial remnants of malassez 
 presented in the roots surface , principal location of the lpc , play a role .
the diagnosis of lpc should be restricted to cysts that are located in the 
 periodontal side .
differentiation between the original lesion and inflammatory cysts 
 and keratocystic odontogenic tumours should be based on clinical , radiographic and 
 pathohistological findings .
radiographically , the cyst presents as a well circumscribed round or teardrop - shaped 
 radiolucent area ( generally not exceeding 1 cm in diameter ) with a radiopaque rim , 
 located laterally to the root of a vital tooth .
the periodontal ligament space as a 
 rule is not enlarged and there must not be a communication between the cyst 's cavity 
 and the oral environment [ 5,11,12,19 - 21 ] . occasionally , lpc may be multicystic , and called as 
 odontogenic botryoid cyst due to macro- and microscopic features resemble to " bunch 
 of grapes " ( from the greek word " botrios " ) .
other 
 interradicular radiolucencies must be distinguished from the lpc : anatomic 
 radiolucencies , such as the mental foramen , maxillary sinus and the nutrient canals ; 
 cyst of pulpal origin , other cysts of the jaws , odontomas and other tumours .
it may 
 resemble a cyst that develops laterally through a side channel accessory in a non 
 vital tooth . in a retrospective study of injuries of no endodontic origin , 3.8% 
 cases of lpc responsible for various treatments without success
the histopathology revealed that lpc is a developmental cyst characterized by a thin 
 layer of nonkeratinized epithelium with a thickness of 1 - 5 mm , which resemble the 
 reduced enamel epithelium .
nonkeratinized squamous epithelium is composed of 1 - 5 
 layers of cells displaying a palisade distribution .
the epithelium lining can be 
 rich in epithelial plaques composed of the clear fusiform cells rich in glycogen . 

some areas of the epithelial thickening , referred to as plaques or theca , are 
 commonly found , and the connective tissue subjacent to the epithelium exhibits a 
 zone of hyalinization .
inflammation is not a feature and the walls of the cyst 
 consist of mature collagen fibrous tissue .
however , it is possible to observe the histopathological 
 variant of lpc - botryoid cyst , that should receive a greater attention considering 
 the rate of recurrence   and unusual presentation 
 .
the botryoid cyst represents a histopathological variant which 
 presents with multilocular cystic " grape - like " appearance in the bone . 

histopathological findings shows multiple cystic spaces lined by nonkeratinized 
 stratified squamous epithelium [ 14,24 - 26 ] .
the mobility of mandibular lateral incisor and canine reported by the patient can be 
 justified by the cyst growth .
however , lpc does not reach proportions that are 
 larger than 1 cm   while cysts of 
 inflammatory origin tend to grow continuously . in cases of a vital tooth , lpc can 
 still be clinically confused with cysts that develop in inflammatory processes in 
 cases of advanced periodontal disease , where the presence of periodontal 
 inflammation stimulates epithelial proliferation . in most cases
the differential 
 diagnosis must be established with radicular cysts , in a view of their high 
 frequency .
these lesions are characterized by necrosis of the affected tooth , as a 
 result of which vitality testing proves negative .
follicular or dentigerous cysts 
 are always associated to an impacted tooth ( particularly a lower third molar ) , while 
 primordial cysts are mostly located in the ascending mandibular ramus .
authors 
 suggest the investigation of the possibility of lpc causing isolated bone defects 
 .
it is interesting to know that the soft tissue variant of lpc corresponds to gingival 
 cyst of the adult .
adult gingival cysts 
 present the same histogenesis , location and clinical features as lpcs , though the 
 rests of odontogenic epithelium appear in the soft tissues - not in bone as in the 
 case of lpcs . as a result
finally , the importance of diagnosis is especially related to the differential 
 diagnosis with keratocystic odontogenic tumour due to its aggressive and 
 infiltrative growth leading to high recurrence rates which requires a more invasive 
 treatment .
the keratocystic odontogenic tumour is one of the most aggressive 
 odontogenic tumours due to its relatively high recurrence rate , relatively fast 
 growth , and the tendency to invade adjacent tissues ; it has been reported that it 
 can penetrate even the skull base . 

scharfetter et al .   demonstrated both : 
 slowly and rapidly proliferating areas in different parts of the keratocystic 
 odontogenic tumour epithelium and the connective tissue wall .
he suggested that the 
 invasive growth of keratocystic odontogenic tumour probably resulted from active 
 growth of the connective tissue wall .
other possible explanations for its high 
 recurrence are increased fibrinolytic activity in the cyst wall , increased mitotic 
 activity , epithelial proliferation in the connective tissue , and a residual dental 
 lamina with subsequent new cyst formation .
the bone resorption by the cyst is mediated by activation of 
 osteoclast - like cells   and/or 
 biologically active collagenases .
the enucleation is the treatment for lpc , which can often be done without injury to 
 adjacent teeth .
the recurrence is not common ; it has been reported with 
 the botryoid variant .
the lateral periodontal cyst can be considered in the differential diagnosis when a 
 radioloucent lesion appears adjacent to the roots of vital teeth .
the treatment of choice is 
 surgical removal and subsequent histological evaluation to confirm the diagnosis . 

 abstractbackgroundthe lateral periodontal cyst is considered a developmental odontogenic cyst 
 with unusual occurrence . in most cases 
 it is preliminary diagnosed as a 
 radiographic finding , presenting as well circumscribed or as a round or 
 teardrop - shaped radiolucent area . due to its location 
 it can easily be 
 misdiagnosed as a lesion of endodontic origin . 
 final diagnosis should be 
 based on histopatological examination . 
 the purpose of this paper is to 
 report a classic case of lateral periodontal cyst located in the anterior 
 region of mandible and to review the relevant literature which describes the 
 clinical , radiological and histopathological features of lateral periodontal 
 cysts.methodsa 50 years female patient complained of an asymptomatic gingival swelling in 
 the region between the left mandibular lateral incisor and canine . 
 
 radiographic examination revealed a well circumscribed radiolucency with 
 approximately 0.5 cm diameter with a radiopaque margin between the roots of 
 the left mandibular lateral incisor and canine . 
 the adjacent teeth had vital 
 pulp.resultsa total enucleation of the lesion was performed , and intraoperative 
 examination showed a single lesion with no communication between the cyst 's 
 cavity and the oral environment . 
 histological examination revealed that the 
 lesion was " lateral periodontal cyst of developmental origin " . 
 there was no 
 recurrence or complications for 24 months follow-up.conclusionsthe lateral periodontal cyst can be considered in the differential diagnosis 
 when a radioloucent lesion appears adjacent to the roots of vital teeth . 
 the 
 treatment of choice is surgical removal and subsequent histological 
 evaluation to confirm the diagnosis . 
 relapses are infrequent . 
INTRODUCTION
CASE DESCRIPTION AND RESULTS
DISCUSSION
CONCLUSIONS
ACKNOWLEDGMENTS AND DISCLOSURE STATEMENTS