peripheral odontogenic tumors demonstrate histological characteristics of their intraosseous counterparts , but occur solely in the soft tissue covering the tooth - bearing portion of the mandible and maxilla .
these lesions are also known as extraosseous odontogenic tumors , soft - tissue odontogenic tumors , or odontogenic tumors of the gingiva .
odontogenic myxoma ( om ) is a rare , benign odontogenic mesenchymal tumor arising from the embryonic connective tissue associated with the tooth - forming apparatus .
it was first described by rudolf virchow as myxofibroma in 1863 and was later renamed as odontogenic myxoma by thoma and goldman in 1947 .
the evidence for its odontogenic origin arises from its almost exclusive location in the tooth - bearing areas of the jaws , its occasional association with missing or unerupted teeth , and the presence of odontogenic epithelium .
it is a slow - growing but locally invasive neoplasm , usually occurring in the second or third decade of life .
the occurrence of om in the maxilla is rare as compared to the mandible and most reports show a slight predilection for females .
oms are central lesions occurring in the jaw bones , commonly present as a painless swelling .
pain , displacement of teeth , and paresthesia are uncommon , thus the lesion can reach considerable size before the patient becomes aware of its presence and seeks treatment .
histologically , the tumor closely resembles the mesenchymal portion of a developing tooth . the tumor is not encapsulated and is composed of haphazardly arranged stellate , spindle - shaped , and round cells in an abundant loose myxoid stroma that contains only a few collagen fibrils .
the treatment of this lesion involves surgical enucleation and curettage , which are the favored techniques .
because of its infiltrative character , this lesion is difficult to be curetted and this explains its high recurrence rate .
cryotherapy as an adjunct procedure to curettage can be used to minimize the risk of recurrence .
intraoral soft - tissue myxoma is an extremely rare lesion and only few reports are available in the literature . in this article , a rare case of peripheral myxoma of anterior maxilla in a 41-year - old female patient is reported with emphasis on review of relevant literature .
a 41-year - old female patient was referred to our department with history of a slowly enlarging gingival mass in the anterior maxilla of 6 months duration .
intraoral examination revealed a solitary , non - tender swelling on the labial gingiva of the left maxilla in relation to 21 and 22 , measuring about 1  2 cm [ figure 1 ] .
the lesion was firm in consistency and the mucosa covering the lesion was normal in color ; no mobility of the regional teeth was seen .
no radiographic changes were seen associated with the lesion [ figure 2 ] . based on the overall findings , provisional diagnosis of fibroma was made .
intraoral photograph showing the lesion on labial gingiva of left maxilla radiograph showing no bony changes the lesion was surgically excised under local anesthesia and subjected to histological examination .
microscopic examination of hematoxylin and eosin stained section demonstrated atrophic , parakeratinized stratified squamous surface epithelium [ figure 3 ] .
the tumor was composed of loosely arranged spindle- and stellate - shaped fibroblasts with small round nuclei suspended in a delicate network of collagen fibrils [ figures 4 and 5 ] .
hematoxylin and eosin stained section showing atrophic , parakeratinized stratified squamous surface epithelium ( 10 ) loosely arranged spindle - and stellate - shaped fibroblasts with small round nuclei ( 20 ) stellate - shaped fibroblasts in loose myxoid stroma ( 40 )
om is a mesenchymal lesion that mimics microscopically the dental pulp or follicular connective tissue .
the origin of om is believed to be from the mesenchyme of a developing tooth or the periodontal ligament .
some authors had previously associated its origin with a myxomatous change of an odontogenic fibroma or residual foci of embryonic tissue . based on the information gathered from the available literature ,
however , its histological similarity to the stellate reticulum of a developing tooth , its exclusive occurrence in close proximity to the tooth - bearing parts of the jaws , the occasional association with a missing or an unerupted tooth , the presence of odontogenic epithelium in a minority of cases , and the fact that it rarely appears in other parts of the skeleton offer support to an odontogenic origin .
most of the patients reported were young adults with average age ranging from 22.7 to 36.9 years .
it is rarely seen in patients younger than 10 years of age and in adults above the age of 50 .
mandible appears to be more affected than the maxilla , in the ratio of 2.5:1 . in both jaws ,
oms commonly occur centrally within the bone of the jaws , whereas our case was located peripherally on the gingiva .
buchner et al . analyzed one of the largest series of odontogenic tumors reported from one source and not even a single case of peripheral myxoma of maxillary gingiva was reported by them .
cases of maxillary peripheral om of maxillary gingiva have been reported in the literature by perrotti et al .
out of these six cases , only two cases were reported in the anterior maxillary gingiva .
om is commonly reported as a slow - growing tumor that is generally asymptomatic , although some patients experience progressive pain in lesions involving maxilla and maxillary sinus , with eventual neurological disturbances .
central myxomas of the jaw have a tendency for extensive bone destruction , invasion into surrounding structures , and a relatively high recurrence rate ; however , metastasis is rare .
our case of soft - tissue myxoma was slow growing and localized in nature , with no evidence of recurrence or metastasis .
these tumors usually show variable radiographic features ranging from small unilocular lesions to large multilocular lesions , which often displace the teeth or resorb the roots .
 soap bubble ,   tennis racket ,   wispy ,  and  spider - web  appearance . since our case was peripherally located in the gingiva , it showed no radiographic changes .
the lesion is not encapsulated and is characterized by a proliferation of few rounded cells , fusiform cells , and star cells in an abundant myxomatous stroma with few collagen fibers .
small islands of odontogenic epithelial tissue can occasionally be found scattered in such a stroma .
om has to be differentiated from other jaw tumors showing myxoid degeneration , such as myxoid neurofibroma , myxoid liposarcoma , and chondromyxoid fibroma .
chondromyxoid fibroma shows areas of cartilaginous differentiation , whereas myxoid neurofibromas tend to have scattered lesional cells that are s-100 positive .
immunohistochemically , cells of oms stain positively for transferrin , ferritin , alpha - l - antichymotrypsin , alpha - l - antitrypsin , s-100 protein , and vimentin ; however , neuron - specific enolase , s-100 alpha and beta subunits , factor viii - related antigen , and cytokeratin are negative .
the lack of capsule and its infiltrative growth pattern are responsible for high rate of recurrence when conservative enucleation and curettage are performed .
oms show a locally aggressive behavior and high recurrence and , hence , call for radical resection .
however , soft - tissue myxoma is not reported to cause recurrence or metastasis ; hence , carefully planned conservative treatment or semi - radical approach is justified in these cases . in the present case , the tumor was completely removed by local surgical excision and there was no recurrence 6 months after surgery .
 odontogenic myxoma comprises 3 - 6% of all odontogenic tumors . 
 odontogenic myxomas are relatively rare benign mesenchymal tumors found exclusively in the tooth - bearing areas of the jaw and are usually located centrally in the mandible . 
 soft - tissue localization is rarely seen and is classified as peripheral myxoma . 
 peripheral myxoma is slow growing and less aggressive , as compared to the central myxoma . 
 it has a low recurrence rate . till date , 
 only few cases of maxillary gingival myxomas are reported in the literature . here 
 , we present an unusual case of primary peripheral odontogenic myxoma occurring in the gingiva of anterior maxilla in a 41-year - old female patient . 
INTRODUCTION
CASE REPORT
DISCUSSION