it is associated with multiple factors including : inflammation , hormonal , drug use , neoplasm , genetic , systemic and idiopathic . despite most of gingival overgrowths are generalized , occasionally this dimorphism can also show a localized gingival enlargement as a consequence of a long - standing proliferative and expansive process in the underlying structures : maxillary bone , periodontal ligament or dental tissues . odontogenic tumours constitute a cluster of neoplasms that are derived from tissues and/or tissue remnants with potential to develop different dental tissues . odontogenic myxoma ( om ) is a benign , locally invasive and aggressive , non - metastasizing neoplasm of the jaw bones . , the lesion may reach a considerable size before the patient discovers its existence . according to the world health organization classification odontogenic myxoma / myxofibroma , is composed of cells from the mesenchyme and/or odontogenic ectomesenchyme with or without odontogenic epithelium . it is uncapsulated and poorly demarcated , thus permeating the surrounding bone and soft tissue by expansion rather than as a result of cellular growth . microscopically these lesions are characterized by stellate and spindle - shaped cells embedded in a richly myxoid extracellular matrix , with little collagen . these cells present long cytoplasmatic prolongations that give to the tissue characteristics of immature mesenchyma . radiographically , the tumour is seen as a unilocular or multilocular radiolucent lesion with well - defined borders , some of them having sclerotic trabeculations with different appearances . displacement of teeth is a relatively common finding , although root resorption is rarely seen . current treatment ranges from curettage to block resection with wide margins with different rates of recurrence . indeed , there is not a clearly established consensus about the surgical treatment of om yet . this case report describes an atypical presentation of localized gingival enlargement associated with a slow - growing om . a 55-year - old black male was attended at dental & oral department in soweto general hospital , arusha ( tanzania ) , complaining of a growing swelling in the area of the anterior left mandible , involving the incisors and canine region ( from 33 to 41 ) . this extreme localized gingival enlargement measured 28  mm33  mm in diameter with very well - defined contour and spherical shape . it is also remarkable that the extreme volume of this gingival overgrowth was mainly at the expense of the inserted broadband gingival distension . however , mucogingival line was completely preserved anatomically in spite of the huge expansion and long evolution of the process . lesion size made difficult a correct lip - seal , caused gingival trauma during mastication and induced local tooth displacement in the affected area ( figure 1 ) . no dental mobility was noted and dental vitality was normal . a moderate chronic periodontitis with abundant supra and sub gingival calculus was diagnosed . deep gingival pockets  pseudo pockets  with slight bleeding were registered on the periodontal charting around the localized enlargement . radiographically , there was an unilocular radiolucent lesion , inducing root displacement without resorption , between 33 and 32 teeth with well - defined borders suggesting a cystic ,  soap bubble ' lesion . a computerized tomography was performed , showing an expansive and osteolytic single left mandibular lesion , with buccal and lingual cortical bone destruction and some internal calcifications but no compartments ( figure 2 ) . this patient was treated through a collaborative program supported by a nonprofit professional partnership . with the presumptive diagnosis , according to the clinical features and the local discomfort produced by the lesion , a conservative surgery with enucleation and curettage was performed without preoperative biopsy . periodontal internal bevel incision was designed , preserving the enormous broadband of keratinized gingiva , like a full - thickness flap procedure in the mandibular symphysis region . after a thoroughly curettage of the quite soft tumoural tissue an important infrabony defect appeared which caused a considerable denuded radicular surface of the involved teeth ( figure 3a ) . close to the amelocementaria line , a cortical protuberance ( 57  mm ) , consequence of the expansive process , had to be regularized in order to get some autologous bone and better flap adaptation . the whole defect was filled using a mixture of the bone previously collected and a bone graft substitute straumann bone ceramic  ( porous biphasic calcium phosphate ) . some reabsorbable haemostat chips of collagen diacoll  ( collagen of porcine origin ) were also used to stabilize this mixture . the adjacent gingival area which had been in intimate contact with this lesion for so many years , presented a deep fibrotic reaction . this abnormal thick layer , adhering to the connective gingival tissue , was removed after being carefully dissected . tissue submitted for histopathological analysis consisted of several soft pieces that altogether measured up to 25  mm15  mm5  mm with a gray - whitish , translucent , mucinous appearance including an osseous fragment 4  mm long . the material was submitted  in to ' for histology ( figure 3b ) . microscopically , the lesion was made up of an abundant loose mucoid or myxoid stroma with evenly distributed round cells with scarce randomly oriented spindle- or stellate - shaped cells of mesenchymal origin alternating with more highly cellular areas and eosinophilic areas of collagen deposition ( figure 4 ) . neither cellular pleomorphism , nor multinucleated cells , nor mitotic activity nor epithelial odontogenic rests were seen . since its original description by thoma and goldman in 1947 , the nature of odontogenic myxomas has been a matter of controversy . these neoplasms are thought to be derived from the mesenchyme of a developing tooth or from the periodontal ligament . however , some studies have found that the cells and the extracellular matrix of om are different from the ectomesenchymal tissues of developing tooth . odontogenic myxoma exhibits slow and asymptomatic expansion , sometimes resulting in a perforation of the cortical borders of the bone affected . radiological examination plays a crucial role for the differential diagnosis of om , which includes other pathological conditions like : odontogenic fibroma , fibrous dysplasia , ameloblastoma , dentigerous cyst , odontogenic keratocyst , central giant cell granuloma , osteosarcoma , fibrosarcoma , ossifying fibroma and chondrosarcoma . although oms can be found in several areas in both jawbones , the mandible is affected more frequently than the maxilla , and the posterior region is the most frequently affected location in both sites . indeed , there is not a clearly established consensus about the surgical treatment of om yet . according to different authors , the recommended treatment modality depending on tumour size is either radical resection or conservative tumour excision . different procedures have been proposed in the literature for oms : enucleation and peripheral ostectomy , cryotherapy and radiotherapy . nevertheless , the most used options remain enucleation with curettage and resection . the reported rate of recurrence after resection seems to be noticeably lower than after enucleation and curettage . the preferred protocol proposed by some authors is to perform a conservative surgery by enucleation and curettage when lesions are smaller than 3  cm and segmental resection with immediate reconstruction when bigger lesions are present . other authors indicate a surgical treatment for om that resembles the management for ameloblastoma solid type , especially when locally aggressive behaviour is present which includes : cortical bone perforation , major tumour expansion and adjacent tissue infiltration in a short period of time ( weeks to months ) . a radical primary resection of the tumour with maximal preservation of surrounding anatomic structures is necessary with healthy anatomical borders of 0.51  cm beyond the radiographic tumour borders . some authors use different bone grafts or allograft materials for filling residual bone defects after surgery . the autologous bone graft has ostoinductive , osteoconductive and osteogenetic properties and prevent from any possible viral infections transmission . however , the need of a second surgical donor site increases morbidity and stress for the patient , and the amount of bone tissue available is limited . fresh - frozen human bone processed by the tissue bank , which provides osteoinductive and osteoconductive properties with major availability of bone for filling defects , can be considered a safe choice . bone - graft substitutes should be osteoconductive , osteoinductive , biocompatible , bioresorbable , structurally similar to bone , easy to use and cost - effective . these recurrences are the result of local invasion into cancellous bone beyond radiographically visible margins in the absence of encapsulation . the nature of this lesion , without a sheath but with an infiltrative growth of the myxomatous tissue into the adjacent bone , determines the high rate of relapse when conservative enucleation and curettage are performed . other odontogenic tumours , like the keratocyst or the ameloblastoma show higher recurrence rates of 30%58.3% and 55%90% , respectively . these patients should be monitored for at least 2 years after the surgical intervention due to the higher rate of recurrence during this period . to the best of our knowledge , there are no previous reports about such an extreme localized gingival enlargement associated with an odontogenic myxoma / myxofibroma for more than 10 years . this lesion involves periodontal tissues , inducing a large gingival expansive process in relation to a subjacent tumoural pathology . this case is especially interesting because of its singularity , slow growing and for the extreme gingival localized dimorphism . it is also remarkable that the extreme volume of this overgrowth was mainly at the expense of the inserted broadband gingival distension , while the mucogingival line reference was anatomically preserved . although histopathology provides the final diagnosis , radiological examination also plays an important role in the differential diagnosis . the management of choice is surgical and ranges from enucleation and curettage to complete resection and peripheral osteotomy according to its size . in this case , after 12-month follow - up , no evidence of recurrence was found . clinicians should be aware that any gingival enlargement can be of neoplastic nature although it could mimic the features of the much more common inflammatory processes , particularly at early stages , to avoid diagnostic pitfalls and to indicate the appropriate treatment .
unusual presentation of localized gingival enlargement associated with a subjacent tumoural pathology is reported . 
 the patient was a 55-year - old black male , whose chief complaint was a progressive gingival overgrowth for more than ten years , in the buccal area of the anterior left mandible . according to the clinical features and the radiological diagnosis of odontogenic keratocyst , 
 a conservative surgery with enucleation and curettage was performed . 
 tissue submitted for histopathological analysis rendered the diagnosis of odontogenic myxoma . after 12-month of follow - up , no evidence of recurrence was found . 
 clinicians should be cautious when facing any gingival enlargement to avoid diagnostic pitfalls and to indicate the appropriate treatment .