ewing 's sarcoma ( es ) is a rare malignant small round cell tumor that primarily affects the skeletal system .
it accounts for 4 to 10% of all types of bone cancer , with long bones and pelvis being the most common locations .
it affects mainly adolescents and young adults and is rarely seen before the age of 5 and after the age of 30 .
clinically , this tumor has an aggressive behavior characterized by rapid growth and high probability of micrometastasis at diagnosis .
an 11-year - old girl presented to department of oral and maxillofacial surgery , yenepoya dental college and hospital , deralakatte , mangalore , with the complaint of swelling on the left side of the face [ figure 1 ] .
the swelling started 6 months back which gradually enlarged to present size . on examination ,
extra orally a diffuse swelling was seen on left side of face which extended superiorly up to ala tragus line , anteriorly from about 2 cm posterior to commisure of mouth to angle of the mandible .
intra oral examination revealed mixed dentition and swelling extending from left mandibular canine to left mandibular second molar [ figure 2 ] . on palpation ,
bi - digital palpation revealed expansion of the buccal plate , no perforation of buccal / lingual cortex and no paresthesia of mucosa or lower lip were seen .
grade iii mobility was seen on all the teeth from left mandibular canine to left mandibular second molar , which were non tender on percussion .
the intra oral periapical radiograph shows radiolucency near the mandibular teeth [ figure 3 ] .
intra oral periapical radiograph showing radiolucency near the mandibular teeth the ct scan findings revealed the following : an ill - defined expansile cystic lesion was seen in the body of the mandible on left side and also thinning and erosion of buccal cortex was also noticed [ figure 4 ] .
the results of hematological and biochemical investigations were within normal limits . under local anesthesia , extraction of the mobile teeth left mandibular first molar was performed and the tissue sample obtained through the extraction socket was sent for histopathological examination .
extracted tooth specimen for biopsy on microscopic examination , h and e stained sections showed sheets of uniform , small , round cells arranged in diffuse pattern , with indistinct outline , scanty cytoplasm , and well - defined nuclear outline , with round to oval nucleus and inconspicuous nucleoli .
a diagnosis of malignant small round cell tumor was made based on the above histopathological findings .
histopathological picture a panel of immunohistochemical markers namely cd99 , cd3 , cd20 , chr , mpo , desmin , and syn were used to rule out other small round cell tumors .
tissue sections showed positive expression for cd99 ( mic2 ) , with characteristic membranous pattern , confirming the diagnosis of ewing 's sarcoma bone scan was also advised which revealed reduced uptake over the body of left mandible without rim of enhanced uptake .
a surgical procedure was performed to resect the malignant tissue with generous surgical margins and to reconstruct the resulting defect .
intraoperative surgical pictures the postoperative panoramic radiograph revealed a well - aligned reconstruction with intact plating ( 6 months post operative orthopantamograph ) adjuant chemotherapy comprised 20 weeks ( 3 cycles ) of treatment with a four - drug regimen which were vincristine [ vc ] , dactinomycin [ ac ] , cyclophosphamide [ cp ] and doxorubicin [ ad ] after surgery .
ewing 's sarcoma ( es ) is a rare malignant small round cell tumor that primarily affects the skeletal system .
it accounts for 4 to 10% of all types of bone cancer , with long bones and pelvis being the most common locations .
it affects mainly adolescents and young adults and is rarely seen before the age of 5 and after the age of 30 .
clinically , this tumor has an aggressive behavior characterized by rapid growth and high probability of micrometastasis at diagnosis .
es is a malignant neoplasm that primarily affects long bones of the extremities with nearly 50% of reported cases involving the femur and pelvis .
the majority of the patients affected are between the ages 5 and 20 , whereas the disease is distinctly uncommon in individuals before age 5 and after age 30 ( braz dent ) .
es arising from the bones of the head and neck region is exceedingly uncommon . when it occurs in the jaw , mandible is more frequently affected than the maxilla .
modern treatments are based on combined modality of treatment : local therapy ( surgery and/or radiotherapy to the main tumor ) followed by chemotherapy(for management of micrometastasis ) .
the present case was positive for cd99 , vimentin and desmin and negative for other immunomarkers , leading to a diagnosis of es .
if root amputation surgery is performed due to an extensive radiolucent lesion , histopathological evaluation should be mandatory .
primary bony reconstruction bears the risk of second intervention when dealing with es in the mandible .
 ewing 's sarcoma is a malignant tumor of bones that primarily affects children and young adults . 
 the true origin of this small round cell lesion still remains controversial . 
 it was originally described by james ewing in 1921 as arising from undifferentiated osseous mesenchymal cells ; however , recent studies suggest that ewing 's tumor might be neuroectodermally derived from various degrees of differentiation of the primitive neural tissues 
 . this paper reports a rare case of es of the mandible in an 11-year - old girl , which had been previously misdiagnosed and treated as a dental abscess . in the clinical examination , a hard immobile expansive mass of 2 cm diameter 
 was observed on the left side of the mandible . 
 radiographic examination revealed a diffuse radiolucent lesion with ill - defined borders and wide vestibular bone plate destruction . 
 microscopically , the tumor was composed by monotonous small round cells that exhibited immunoreactivity for cd99 , vimentin and desmin . 
 surgical resection of mandible followed by mandibular reconstruction was adopted . 
 the patient was subjected to multiagent chemotherapy with vincristine [ vc ] , dactinomycin [ ac ] , cyclophosphamide [ cp ] and doxorubicin [ ad ] ) . 
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