ewing 's sarcoma ( ews ) is an aggressive osteolytic tumor of bone and rapidly disseminates to other sites . it shares the histological features with other malignant small round cell tumors ( msrct ) . therefore the defining cytogenetic abnormality is a balanced translocation t(11;22 ) expressing the ews / friend leukemia integration-1 ( fli-1 ) chimeric fusion protein . metastatic ews should be diagnosed early as it is difficult to control and treatment needs a multimodality approach constituting chemotherapy , surgery and radiotherapy . the case we present here is a 14-year - old female child who presented with low backache since 1 year followed by right eye proptosis for 4 months and swelling over right side chest wall since 3 months [ figure 1a ] . magnetic resonance imaging revealed involvement of posterior element of the sacrum with l5 vertebra and a presacral soft tissue mass measuring 11.8 cm  7.5 cm . large abdominal soft tissue mass in pancreatic region measuring 6.2 cm  4.8 cm was seen indicating a possibility of nodal involvement . venous invasion with tumor thrombus in left internal and common iliac veins and lower inferior vena cava was noticed . fine needle aspiration smears from orbital mass were highly cellular showing cells arranged both in clusters and singly dispersed [ figure 1c ] . cells were both light and dark types with a thin rim of pale cytoplasm and small round nuclei having small inconspicuous nucleoli . rosette like structures , but no true rosettes were seen . considering the clinical presentation , a provisional diagnosis of msrct possibly ews was given . two tru - cut biopsy samples were taken from the same mass . from one sample , paraffin block was prepared . histologically the tumor cells were arranged in irregular nests separated by dense fibrous stroma [ figure 2a ] . the cells were 1 - 2 times larger than small lymphocytes with scant eosinophilic or clear cytoplasm , centrally placed round nuclei with finely distributed chromatin and inconspicuous nucleoli [ figure 2b ] . mitotic figures were few ; necrosis scanty and rosettes were not seen indicating the absence of neural differentiation . the paraffin block was subjected to cd99 immunohistochemical marker and was strongly and diffusely positive [ figure 2c ] . other sample was preserved in trizol reagent for molecular genetic analysis to look for ews - fli-1 translocation . total ribonucleic acid ( rna ) was extracted from snap frozen tumor tissue using trizol reagent . reverse transcription - polymerase chain reaction ( rt - pcr ) was performed with abl oligonucleotide primer to check for the quality of the rna isolated , which amplified a 300 bp product . the ews - fli-1 product was type 1 fusion ( 330 bp ) [ figure 2d ] . ( c ) cytology of orbital mass ( h and e 100 ) ( a ) photomicrograph showing small round cells in tissue section ( h and e 100 ) . ews is a primary nonosteogenic malignant tumor of bone with peak incidence in second decade of life . we report the above case in a 14-year - old girl with involvement of l5 vertebra and sacral bone with metastasis to multiple sites at the time of presentation . early and correct diagnosis of ews is essential for clinical management since it belongs to the group of primary msrct . this group includes neuroblastoma , lymphoma , desmoplastic small round cell tumor and rhabdomyosarcoma besides ews and peripheral neuroectodermal tumor where neural differentiation is seen in addition to all the features of ews . since the morphologic features in all these tumors are more or less similar , one takes the help of special stains in addition to other ancillary techniques for differentiation of one from the other . pas stain detects the presence of large amounts of intracellular glycogen , but it is a nonspecific finding since many childhood tumors contain it and up to 35% of ews may not contain detectable glycogen . cd99 is a useful marker in the differential diagnosis of these tumors as 90% of ews / peripheral neuroectodermal tumors stain positive . though neuroblastoma , the main tumor in the differential diagnosis is not positive for cd99 , it is seen to be positive in other malignant small cell tumors such as small cell osteosarcoma , lymphoblastic lymphoma , mesenchymal chondrosarcoma , and alveolar rhabdomyosarcoma . the chromosome 22q12 breakpoints are clustered within a single gene designated ews and chromosome 11q24 are within a gene called fli-1 . this translocation results in the expression of an aberrant hybrid protein in which the n - terminal part of ews is linked to deoxyribonucleic acid binding domain ( ets domain ) of the fli-1 transcription factor . the ews - fli-1 protein is thought to be responsible for the origin of ews . kelleher and thomas have suggested some promising therapeutics like ews - fli-1 gene silencing , growth factor - i receptor antagonists , mammalian target of rapamycin inhibition , kit oncoprotein targeting , etc . although cytogenetic analysis can detect a wide variety of chromosomal translocations , it is time consuming , technically difficult and success rate is variable . hence , we used the reverse transcription followed by pcr assay for detecting the presence and type of ews / fli-1 fusion transcript . the specific genetic alterations among other small round cell tumors can establish the genotypic diagnosis of these tumors . the most common site to which ews spreads , or metastasizes , is the lungs . metastatic ewing 's sarcoma is typically difficult to control , though patients with lung metastases have a better prognosis than patients with other distant metastases . following diagnosis by tru - cut biopsy and cd99 immunopositivity ( which was confirmed by rt - pcr analysis ) , our patient received three cycles of chemotherapy and no radiotherapy . after one cycle of chemotherapy , the right eye proptosis and swelling over the chest wall disappeared [ figure 1b ] . however after receiving next two cycles , she became bedridden and before receiving the 4 course of chemotherapy , the patient expired ( within 1 year of diagnosis ) . this case exemplifies the idea that every new lesion in a patient with ews should be considered as a possible metastasis .
ewing 's sarcoma ( ews ) is an undifferentiated sarcoma of bone . 
 its morphologic appearance resembles many other malignant small round cell tumors . due to the morphologic overlap 
 , there is diagnostic difficulty and for accurate diagnosis , requires special studies such as immunohistochemistry , electron microscopy , cytogenetics , and molecular genetic analysis . 
 we report a case of metastatic ews from orbital mass in a 14-year - old female child diagnosed by cytology after clinicopathologic evaluation . 
 she presented with low back ache of 1 year followed by proptosis of the right eye and swelling of the right side chest wall . 
 cytosmear and tru - cut biopsy was taken from the orbital mass showed features of ews . 
 it was confirmed later by further studies including demonstration of ews / friend leukemia integration-1 fusion gene by molecular genetic analysis .