ewing sarcoma is a bone neoplasm that usually occurs in children and young adults and which can extend into the soft tissues . we report a case of ewing 's tumour involving the left anterolateral muscle group of the abdominal wall without associated skeletal location and we describe ultrasonography and computed tomography ( ct ) imaging features of this disorder . a 35-year - old woman presented with a 2-month history of a painful swelling of the left abdominal wall . physical examination revealed an irregular mass approximately 6 cm in diameter on the left side of the abdominal wall . ultrasonographic evaluation revealed a large hypoechoic and inhomogeneous well - defined soft tissue mass , developed in the left anterolateral muscles of the abdominal wall measuring about 6.5  4 cm ( fig . the study in doppler mode showed mixed , arterial and venous flow signals within part of the tumour ( fig . ( a ) transverse gray - scale sonogram showing a large hypoechoic and inhomogeneous well - defined soft tissue mass developed in the left anterolateral abdominal wall . ( a ) transverse gray - scale sonogram showing a large hypoechoic and inhomogeneous well - defined soft tissue mass developed in the left anterolateral abdominal wall . an abdominal helical ct evaluation was performed using a helical single detector ct ( siemens somatom plus 4 ) . scanning covered from the diaphragm to the pubic bone before and after intravenous contrast with arterial and portal venous phases . the patient received intravenous contrast material ( scanlux ) administered at a rate of 3 ml / s and a volume of 120 ml with a power injector . the unenhanced study showed a large mass involving the left anterolateral muscle group of the abdominal wall . this mass was isodense to the adjacent muscles with hypodense areas and no evidence of calcification or fatty areas ( fig . after bolus contrast administration , the mass was well circumscribed and lobulated with heterogeneous but intense enhancement ( fig . ( a ) axial ct slice showing a mass involving muscles of the left anterolateral abdominal wall . ( b ) enhanced slice , after bolus contrast administration , showing a well - defined mass with intense and inhomogenous enhancement . ( a ) axial ct slice showing a mass involving muscles of the left anterolateral abdominal wall . ( b ) enhanced slice , after bolus contrast administration , showing a well - defined mass with intense and inhomogenous enhancement . a whole body bone scintigraphy study showed normal skeletal uptake of tracer and no evidence of bone involvement . according to the imaging findings , the patient underwent an incisional biopsy and the tumour was determined to have the microscopic characteristics of a ewing sarcoma involving the soft tissues . neoadjuvant chemotherapy was carried out including vincristin , cyclophosphamid and adriamycin for three cycles but the patient showed a poor response and surgery was required . ewing sarcoma commonly arises from bone and it can involve soft tissues at the time of the diagnosis . rarely , ewing sarcoma may have an extraskeletal origin . soft tissue ewing sarcoma is a rapidly growing , round - cell , malignant tumour which can reach 10 cm by the time of the diagnosis . young adolescents and adults between the ages of 10 and 30 years are predominantly affected with a slight predominance in males . however , some cases have been reported in patients between 14 months and 77 years of age . commonly affected extraskeletal sites are the paravertebral spaces , lower extremities , head and neck , and pelvis . other rare reported locations of extraskeletal ewing sarcoma are various and include the retroperitoneum , orbit , skin , and chest wall . to the best of our knowledge , only one previous paper reported a ewing sarcoma involving the abdominal wall . it often presents as a well - limited mass which should not be confused with a benign lesion . ultrasonography often shows a hypoechoic and heterogeneous mass with intra - tumour flow signals in a doppler study . ct shows a large , sharply delineated mass which is relatively hypodense or isodense compared to the adjacent muscle . hypodense foci are frequent in the large mass and are due to intratumour necrosis . on magnetic resonance imaging ( mri ) , this tumour is often of low to intermediate signal intensity on t1-weighted images ; of high signal intensity on t2-weighted images , and exhibits heterogeneous contrast enhancement . sometimes , mri shows a homogeneous , moderate enhancement on contrast - enhanced t1-weighted images . the secondary osseous involvement is rare even when the mass is located near a bone segment . diagnosis is confirmed by ct - guided core - needle biopsy or pathological analysis of the operative specimen . extraskeletal ewing sarcoma is confirmed by characteristic features on histologic analysis , histochemistry , immunohistochemistry and electron microscopy . differential diagnoses include other small , blue round cell tumours ( sbrcts ) and other members of the ewing family of tumours such as the primitive neuroectodermal tumour ( pnet ) . tumours that are not appropriate for surgical resection or have positive margins are treated with radiation . the prognosis for extraskeletal ewing sarcoma appears more favourable than that of ewing sarcoma in bone . two previously published series devoted to the study of extraskeletal ewing sarcoma stated that it is a curable disease and has the best prognosis in young patients ( age < 16 years ) treated with complete resection with wide surgical margins in conjunction with chemotherapy . ahmad et al . also demonstrated that tumour size did not have a significant effect on overall 5-year survival or disease - free survival . there was no differences in overall or disease - free survival between the patients with metastatic disease and those without . imaging is useful for evaluation of the rate of resectability and the tumour response to treatment . tumours that are not appropriate for surgical resection or have positive margins are treated with radiotherapy . in summary , although its radiological features are non - specific , it should be kept in mind in the differential diagnosis of soft tissue tumours in young people .
abstractewing sarcoma is most commonly a bone tumour which has usually extended into the soft tissues at the time of diagnosis . 
 exceptionally , this tumour can have an extraskeletal origin . 
 clinical or imaging findings are non - specific and diagnosis is based on histology . 
 we report a case of an extraskeletal ewing sarcoma developed in the soft tissues of the abdominal wall in a 35-year - old woman who presented a painful abdominal wall tumefaction . 
 ultrasongraphy and computed tomography showed a large , well - defined soft tissue mass developed in the left anterolateral muscle group of the abdominal wall . 
 surgical biopsy was performed and an extraskeletal ewing sarcoma was identified histologically .