the world health organization defines abc as an expansive osteolytic lesion consisting of blood - filled spaces and channels divided by connective tissue septa that contains osteoid - like tissue and osteoclast - like giant cells .
abc commonly occur in the long bones ( 50% ) , vertebral column ( 20% ) , but in maxillofacial region , two - thirds were located in mandible ( body of the mandible 40% , the ramus 30% and the angle 19% ) and one - third in the maxilla representing about only 1.5% of all nonepithelial cysts of the jaws .
it usually occurs in young persons , below 20 years of age , and shows no gender predilection .
this case represents unusual mandibular condylar pathology ( abc ) which was treated by resection and metallic condylar head add - on system ( ortho max , india ) as a primary reconstructive option .
an 18-year - old female reported to our center with the chief complaint of swelling in the region just in front of right ear from 5 months with no history of previous trauma to the region .
clinical examination revealed a smooth , firm , but diffuse swelling of size 4 cm  4 cm ( approximately ) was present in the right preauricular region [ figure 1 ] . on examination , there was the presence of mild tenderness , deviation of mandible on opening , and nerve of facial expression was unaffected .
mouth opening was mildly reduced to 26 mm . swelling and facial asymmetry present on right side of face on investigation
, hemogram showed hb 12 g% , total leukocyte count 8200 cells / cmm , total platelet count 2.2 lac / cmm and dc showed polymorphs 74% , lymphocytes 20% , eosinophils 6% .
the serum alkaline phosphates 177 iu / l , serum phosphorus 3.5 mg / dl and serum calcium ( ionized ) 1.09
mmol / l were within normal limits . on panoramic examination , there was a radiolucent lesion in the area of right mandibular condyle .
further imaging with computed tomography ( ct ) revealed a 3.4 cm  3.3 cm sized expanded , cystic lesion of the right mandibular condyle with septa and fluid levels , suggesting a diagnosis of abc [ figure 2 ] .
computed tomography view of the condylar pathology extraoral approach was used for gross condylar resection with the articular disk in place and alloplastic metallic condylar head add - on system [ figure 3 ] as a primary reconstructive option .
histopathological examination of resected condyle revealed a wide fibrous stroma with cystic spaces lined by uneven band of fibroblasts , stromal cells , and osteoclastic giant cells with hemorrhage in lumina of cysts suggestive of abc [ figures 4 and 5 ] .
fourty - eight hours postoperatively , an active mouth exercise was conducted for 34 times a day for 2 weeks .
on postoperative evaluation , all the branches of facial nerve were functioning normally [ figure 6 ] .
the patient has been reviewed on a monthly basis for 1-year without any signs of discomfort and recurrence [ figure 7 ] with the satisfactorily functioning condylar head add - on system , normal mouth opening [ figure 8 ] , and mandibular border movements .
metallic condylar head add - on system in place after resection low magnification view showing cystic spaces lined by fibroblasts with hemorrhage in lumina ( h and e stain ) high magnification view showing uneven band of fibroblasts , stromal cells , and osteoclastic giant cells ( h and e stain ) normal facial nerve function postoperatively panoramic view of condylar prosthesis after 1-year satisfactorily working temporomandibular joint after 1-year
the abc is a benign solitary osseous lesion recognized as a distinct clinicopathological entity by jaffe and lichtenstein in 1942 .
various theories where put forward like trauma , alteration of local hemodynamics , subperiosteal intraosseous hematoma , and secondary phenomena occurring in primary cystic lesions of bone and tumors but , the etiology of abc still remains elusive and unclear .
the abc has been classified as primary and secondary were primary may be divided into congenital or acquired type .
histopathologically , the vascular variant is more common and consists of about 95% of total cases of abc while the solid type is rare , occurring in only 58% cases .
the clinical signs and symptoms of abc are nonspecific and do not lead to any clinical diagnosis . similarly in this case also , there was presence of swelling , asymmetry and associated pain secondary to temporomandibular joint dysfunction , ct scan showing different fluid levels and histologically , blood - filled spaces within connective tissue stroma , and osteoclastic multinucleated giant cells which is pathognomonic of abc together has led to the definitive diagnosis of abc .
concluded that block resection has shown comparatively good results with minimal recurrence ( 20% comparing to 60% in curettage ) and also recommended close postoperative follow - up of at least 12 months especially on condylar involvement as recurrence of condylar abcs ( 40% ) was comparatively higher than noncondylar jaw abcs ( 13% ) . in this case also after following similar protocol , the outcome was satisfactory at the end of 1-year .
comparing the results of 8 cases of reconstruction in abc condyle including this case [ table 1 ] we found that , 62.5% cases has gone for costochondral graft either as a primary or in recurrence cases as an reconstructive option , while 25% cases has taken condylar prosthesis as an reconstructive option .
used condylar head add - on system in recurrence case with satisfactory results over a period of 8 months .
replacement reported the complication rate of 10.6% over a minimum follow - up period of 3 years .
our results matched with these studies [ table 2 ] represent the postoperative 1-year status of the patient .
reconstruction review of abc condyle resected cases postoperative 1-year patient status findings from this cases states that , bypassing the risk and morbidity of donor site especially in female patients were donor site is a surgical dilemma for surgeon and patient both ; metallic condylar prosthesis can be used as a satisfactory alternative to autograft in primary condylar reconstruction .
however , we recommend a longer follow - up for better evaluation of function and complications if any .
condylar head add - on system has shown promising and satisfactory results with avoiding obvious disadvantages of autograft like surgical risk and donor site morbidity .
it can be considered as a preferred primary reconstructive option , reserving the autograft for recurrence cases .
the authors certify that they have obtained all appropriate patient consent forms . in the form the patient(s )
has / have given his / her / their consent for his / her / their images and other clinical information to be reported in the journal .
the patients understand that their names and initials will not be published and due efforts will be made to conceal their identity , but anonymity can not be guaranteed .
the authors certify that they have obtained all appropriate patient consent forms . in the form the patient(s )
has / have given his / her / their consent for his / her / their images and other clinical information to be reported in the journal .
the patients understand that their names and initials will not be published and due efforts will be made to conceal their identity , but anonymity can not be guaranteed .
 aneurysmal bone cysts ( abcs ) involving condyle are unusual clinical presentation affecting younger group of society with only 12 cases reported till today in english literature . in this case of abc condyle following resection , reconstruction of temporomandibular joint was done by alloplastic condylar prosthesis as a primary choice . 
 monthly basis follow - up was done for 1-year with a successful result . reviewing the reconstructive options used in abc condyle cases we found that the condylar head add - on system 
 has shown a satisfactory result in comparison to costochondral graft with no donor site morbidity . 
 we recommend condylar head add - on system should be preferred as a primary reconstructive option , reserving the autograft for recurrence cases . 