ameloblastomas have been categorized into three biologic variants : cystic ( unicystic ) , solid ( multicystic ) , and peripheral . the literature indicates that the cystic variant is biologically less aggressive and has a better response to enucleation or curettage than the solid ameloblastoma . peripheral tumors are odontogenic tumors , with the histological characteristics of intraosseous ameloblastoma that occur solely in the soft tissues covering the tooth - bearing parts of the jaws . unicystic tumors include those that have been variously referred to as mural ameloblastomas , luminal ameloblastomas , and ameloblastomas arising in dentigerous cysts ( dcs ) . it is a less aggressive variant and it has a low rate of recurrence , although lesions showing mural invasion are an exception and should be treated more agressively . here , we report a case of unicystic ameloblastoma ( ua ) in a 35-year - old female with an unusual large multilocular radiographic appearance on the right body of mandible . multilocular appearance , though not uncommon in ua , the appearance of thin straight septa creates confusion in diagnosing the lesion . this case report illustrates the importance and complexity of differential diagnosis , as the management differs widely for all multilocular lesions . a 35-year - old female patient presented with a chief complaint of swelling in the right lower jaw back region since 3 - 4 months . patient gave history of extraction of right mandibular second and third molars 2 years before the swelling appeared . on examination , extraorally , a non - tender diffuse swelling with variable consistency was present on right mandibular angle region . intraorally , a well - defined swelling was present extending from mesial surface of right first molar to retromolar region , involving the edentulous region in relation to the right mandibular second and third molar teeth [ figure 1 ] . bicortical expansion was present . based on these findings , provisional diagnosis of odontogenic keratocyst ( okc ) the lesion was then aspirated ; a thin straw color fluid was obtained from the lesion , which was sent for protein analysis . an intra - oral swelling involving right edentulous ridge in relation to mandibular second and third molar region with bicortical expansion orthopantamograph revealed [ figure 2 ] , a huge well - defined multilocular radiolucency on the right body of the mandible , extending from the mesial surface of right mandibular first molar to ramus region . the periphery of the lesion is well defined , not surrounded by any sclerotic border . the septa within the lesion are straight and thin- etched and placed perpendicularly at the periphery , giving an appearance of a tennis racket like pattern . the lesion is causing resorption of both mesial and distal roots of right mandibular first molar . the septa within the lesion are thin and straight and placed perpendencularly at the periphery giving an ppearance of tennis  racket . resorption of first molar roots seen multilocular lesions such as ameloblastoma , odontogenic myxoma , and central giant cell granuloma were considered under differential diagnosis based on radiological picture . however , positive aspiration of the lesion is contrast to these lesions . based on aspiration , okc , and dc residual cyst is considered as one of the differential diagnosis due to positive history of extraction prior to swelling . ua is considered as one of the differential diagnosis based on site , clinical picture and positive aspiration . incisional biopsy was performed and sent for histopathological analysis and a diagnosis of ua with mural proliferations was made based on histological picture [ figure 3 ] . the excised specimen was also subjected to histopathological analysis , which confirmed the diagnosis of ua with mural proliferations . post - operative follow - up of the patient had been satisfactory [ figures 4 and 5 ] . histopathology picture showing an ameloblastomatous epithelium , with a cystic lumen into which the epithelial proliferations are seen immediate post - operative extraoral image of the patient immediate post - operative intraoral view of the patient with adequate mouth opening many benign lesions cause mandibular swellings , whose origin can be , attributed to odontogenic or non - odontogenic causes . the most commonly encountered are ameloblastomas , radicular cysts , dcs , okcs , central giant cell granulomas , fibro - osseous lesions and osteomas . the most common tumor of odontogenic origin is ameloblastoma , which develops from epithelial cellular elements and dental tissues in their various phases of development . the unicystic type of ameloblastoma is one of the least encountered variant of the ameloblastoma accounting for about 10 - 15% of all ameloblatomas.[46 ] unicystic type appears more frequently in a younger population ( 3 decade ) than its solid counterpart ( 4 decade ) . in our case , uas were most commonly encountered in posterior mandible , followed by the parasymphysis region , anterior maxilla and the posterior maxilla . the ratio of the maxilla : mandible is 1:7 for the dentigerous variant , versus 1:4.7 for the non - dentigerous type . in our case also the lesion was non - dentigerous type and was present on right body of the mandible extending up to the ramus region . gender distribution shows a slight male predilection with a male : female ratio of 1.6:1 . however , when the tumor is not associated with an unerupted tooth , the gender ratio is reversed to a male to female ratio of 1:1.8 . most of the uas are associated with an impacted tooth , the mandibular third molar being involved most often . in our case , patient is a female , and the lesion is not associated with any unerupted / impacted teeth . as the lesion slowly enlarges , a slight , non - tender swelling becomes apparent on clinical examination . this swelling is the result of an expansion of the cortical plates of the jaw and can be identified by palpation as hard and bony . the radiological features of ua are typically unilocular and there is a round area of radiolucency . it has been suggested that six radiographic patterns for ua can be identified ranging from well - defined unilocular to multilocular . eversole et al . , identified predominant radiographical patterns for ua : unilocular , scalloped , macromultilocular , pericoronal , interradicular , or periapical expansile radiolucencies . where as our case showed atypical multilocular appearance with some straight septa within the lesion . our case should be differentiated from other multilocular lesions like solid ameloblastoma , central giant cell granuloma , odontogenic myxoma , and cystic lesions like okc , dc , and residual cyst . based on fluctuant consistency and positive aspiration all the multilocular lesions have been ruled out . okc produces thick cheesy material instead of thin straw color fluid which is seen in our case . residual cyst also is ruled out because it will not produce so much of expansion as seen in our case . the specimen was sent for histopathological evaluation , which confirmed the diagnosis of ua . in conclusion , ua , a type of ameloblastoma , presents with a variety of clinical , radiological and histopathological features . immunohistochemical studies help us to know the nature of the lesion and also to differentiate the same from other cysts of odontogenic origin . hence , it is essential that studies should be conducted on a large scale in order to know the origin and nature of the lesion .
unicystic ameloblastoma ( ua ) refers to those cystic lesions that show clinical , radiographic , or gross features of a mandibular cyst , but on histologic examination show a typical ameloblastous epithelium lining part of the cystic cavity , with or without luminal and/or mural tumor growth . 
 it accounts for 5 - 15% of all intraosseous ameloblastomas . 
 we report a case of ua in a 35-year - old female with an unusual large multilocular ( tennis racket ) appearance on the right body of mandible and illustrate the importance and complexity of differential diagnosis with a brief review of recent literature .