Impact of FDG PET for staging of Ewing sarcomas and primitive neuroectodermal tumours

AIM: High-grade Ewing sarcomas and Primitive neuroectodermal tumours (PNET) make up the tumours of the Ewing family. Our purpose was to evaluate the value of [18F]fluorodeoxyglucose positron emission tomography (FDG PET) in patients with Ewing tumours. PATIENTS AND METHODS: Twenty-four patients who had PET because of a suspected Ewing tumour during a 5-year period were included in this retrospective study. The images of 33 whole-body FDG PET investigations performed in primary or secondary diagnostics were analysed visually and semi-quantitatively by using standardized uptake values (SUVs). In 14 cases, PET was compared to bone scintigraphy regarding bone lesions. The final diagnosis was based on histology, imaging and follow-up. RESULTS: Histologically, the primary lesions were 10 Ewing sarcoma, 13 PNET and one osteomyelitis. The sensitivity and specificity of an examination-based analysis (presence of Ewing tumour and/or its metastases) were 96 and 78%, respectively. Altogether, 163 focal lesions were evaluated. Sensitivity and specificity regarding individual lesions were 73 and 78%. This lower sensitivity is mainly due to small lesions. In true-positive cases, the mean SUV was 4.54+/-2.79, and the SUVs in two false-positive cases were 4.66 and 1.60. True-positive and false-positive cases could not be differentiated definitively based on SUVs because of overlap and low values in true-positive lesions. In four cases, PET depicted 70 while bone scintigraphy depicted only eight bone metastases. CONCLUSION: An FDG PET investigation is a valuable method in the case of Ewing tumours. PET is superior to bone scintigraphy in the detection of bone metastases of Ewing tumours. For the depiction of small lesions, mainly represented by pulmonary metastases, PET is less sensitive than helical computed tomography. Determination of the role of whole-body FDG PET in diagnostic algorithm needs further investigation.     

Osteogenic and Ewing sarcomas: estimation of necrotic fraction during induction chemotherapy with dynamic contrast-enhanced MR imaging

Dynamic contrast material-enhanced magnetic resonance (MR) images of primary osteogenic sarcoma (n = 19) and Ewing sarcoma (n = 10) were reviewed in 29 patients undergoing induction chemotherapy before surgery. Histogram distributions containing the initial slope and pharmacokinetic model parameters from individual voxels within each tumor were fitted for each patient. The histogram analysis of initial slope from the tumor correlated well with percentage necrosis as determined at pathologic examination (r = 0.60, P <.001), as did a two-compartment pharmacokinetic model (r = 0.64, P <.001). Both methods predicted tumors with clinically important degrees of necrosis (ie, > or =90%) in a large majority of cases. The ability to determine response to induction chemotherapy by means of noninvasive monitoring of necrotic fraction with perfusion MR imaging methods may provide useful prognostic information and help surgical planning.     

Primary Ewing sarcoma of rib

Ewing sarcoma is a relatively common, highly malignant bone tumor that typically occurs in adolescents and young adults aged 10-25 years. Our archives contain 328 cases of histologically proved and radiologically correlated Ewing sarcoma collected in consultation over 40 years. From this series, we identified 34 lesions (10%) arising in ribs. Radiographically, the affected rib was predominantly lytic in most (82%) cases, but mixed lytic-sclerotic (9%) and even predominantly sclerotic (9%) patterns were also encountered. The affected rib was "expanded" in 35% of cases, although the contour change was usually mild. Abnormalities of the affected ipsilateral hemithorax varied from subtle, isolated rib involvement to solitary rib involvement accompanied by complete opacification of the hemithorax. We describe the spectrum of radiologic findings of primary Ewing sarcoma of rib, augmented where appropriate by accompanying pathologic material.     

Radiological features of extraskeletal Ewing sarcoma

The radiological features of extraskeletal Ewing sarcoma were reviewed in 22 patients whose average age was 22 years. Tumours were located in the extremities (11 patients), abdomen or pelvis (six patients) and the chest (five patients). The tumours ranged in size from 2 cm to 20 cm, were mainly well circumscribed and showed no evidence of calcification prior to treatment. Most tumours (13 out of 14) were of low attenuation or contained areas of lower attenuation than muscle on computed tomographic examination, and in six out of seven patients studied by ultrasound the tumours were hypoechoic or partly anechoic. No distinctive post-contrast medium enhancement pattern on CT examination (11 patients) or angiographic features (three patients) were evident. Tumour haemorrhage was a frequent microscopic finding and changes consistent with this were present in one patient on magnetic resonance imaging examination. Distant metastases or local recurrence developed in 13 patients with lung being the most frequent metastatic site (eight patients). Although its radiological features are non-specific, extraskeletal Ewing sarcoma should be included in the differential diagnosis of noncalcified soft-tissue tumours especially in a young age group and where located in an extremity or paravertebral region of the chest.     

Spinal Ewing sarcoma: Misleading appearances

The plain radiographic and computed tomographic (CT) findings in two unusual cases of spinal Ewing sarcoma are reported. Radiographic features resembling neuroblastoma in one case and aneurysmal bone cyst in the other were present. These findings may be misleading and distinguishing characteristics in each case are discussed.     

Pelvic Injuries

Pelvic injuries are an important consideration in trauma patients. This is largely as a result of the major disruptive forces required to fracture the pelvic ring, and the resulting complications that can be expected from major pelvic ring disruption. These can be both immediate (associated visceral injury, hemorrhage, etc.) or delayed (infection, morbidity, etc.), but to a large extent can be anticipated by knowledge of the type of injury force producing the fracture, and specific complications associated with each force of injury. This article will examine pelvic injuries from a mechanistic approach, determining the specific pelvic fracture patterns that are encountered, how they may be imaged best, and what types of complication might be expected.     

Radiation-induced sarcomas of bone

Historically, the literature reveals that the incidence of radiation induced bone sarcomas is very low. Details related to epidemiology cannot be identified, however, because of the difficulty of identifying precisely the patient population at risk for development of the radiation induced sarcoma. The change in character of practice in cancer management with ever increasing numbers of patients receiving both radiation therapy and chemotherapy should alert physicians to the potential for increased incidence of this rare and unusual tumor.     

Primary thoracic sarcomas.

Primary sarcomas of the thorax are rare. The diagnosis is established only after sarcomalike primary lung malignancies and metastatic disease have been excluded. Primary sarcomas of the thorax are classified according to their histologic features and constitute a large group of tumors that occur in the lung, mediastinum, pleura, and chest wall. Angiosarcoma, leiomyosarcoma, rhabdomyosarcoma, and mesothelioma (sarcomatoid variant) are the most common primary intrathoracic sarcomas. Ewing sarcoma, primitive neuroectodermal tumor, chondrosarcoma, malignant fibrous histiocytoma, osteosarcoma, synovial sarcoma, and fibrosarcoma usually arise in the chest wall. Although primary thoracic sarcomas commonly manifest as large, heterogeneous masses, they have a wide spectrum of radiologic manifestations, including solitary pulmonary nodules, central endobronchial tumors, and intraluminal masses within the pulmonary arteries. The different histologic types of sarcomas are frequently indistinguishable at radiologic analysis. However, differences in clinical presentation and the location of the tumor, as well as morphologic features such as calcification within the mass and rib involvement, can be useful in suggesting the appropriate diagnosis. For example, a large rib mass in a child with fever and malaise indicates a Ewing sarcoma, a mass with a calcified matrix is likely a chondrosarcoma or osteosarcoma, and a pulmonary artery mass is likely a leiomyosarcoma.     

Imaging pediatric bone sarcomas

Primary malignant bone tumors are rare and account for about 6% of all new pediatric cancer cases per year in the United States. Identification of the lesion not uncommonly occurs as a result of imaging performed for trauma. Clinical and standard imaging characteristics of the various tumor types are evolving in concert with treatment advancements and clinical trial regimens. This article reviews the 3 most common pediatric bone sarcomas-osteosarcoma, Ewing sarcoma, and chondrosarcoma-and their imaging as applicable to contemporary disease staging and monitoring, and explores the roles of evolving imaging techniques.     

Radiographic appearance of Ewing sarcoma of the hands and feet: report from the Intergroup Ewing Sarcoma Study

Review of current data from the Intergroup Ewing Sarcoma Study (IESS) shows that Ewing sarcoma is rare in bones of the hands and feet. The 12 patients from the IESS protocols with hand or foot Ewing sarcoma are comparable to those already reported in the literature. With the exception of lesions in the calcaneus, the prognosis for disease-free survival is excellent. The radiographic features of hand and foot Ewing sarcoma are generally those of classic Ewing sarcoma: permeation, soft-tissue mass, and, often, associated sclerotic reaction. However, with the exception of sclerosis, features suggesting bone reaction and slow tumor growth in these patients were distinctly uncommon compared with Ewing sarcoma in general. Those radiographic features suggesting aggressive behavior were slightly more common than in the general Ewing population. Even so, neither the radiographic appearance nor the greatest dimension of the radiographic lesion can be shown to contribute significantly to prognostication in these patients. Apparently location of the lesion is important, since in the reported cases in the literature and in this series, lesions of the calcaneus fared poorly. The importance of this set of patients therefore relates to awareness and early recognition of an unusual appearance and location of Ewing sarcoma.     

Ewing’s sarcoma of the thumb

 The case of a 51-year-old man with Ewing’s sarcoma of the thumb is presented. The tumor involved the distal phalanx of the right thumb, associated with an impressive extraskeletal mass. Histology revealed a round cell sarcoma with a positive immunoreactivity with monoclonal antibody O13. Five years after disarticulation at the metacarpophalangeal joint, the patient is alive without recurrence or metastasis.     

Extraskeletal Ewing sarcoma of the buccal space

Extraskeletal Ewing sarcoma (EES) is a rare soft tissue tumor, and EES of the head and neck is particularly rare. Radiographic imaging of these lesions is crucial given their anatomical complexity and infrequent incidence. Conventional EES imaging features include a large, hyperintense, heterogeneously enhancing lesion, with frequent invasion of local structures. In this case report, a 19-year old male presented with left facial swelling and pain. He underwent sclerotherapy and bleomycin treatment for a presumed lymphatic malformation. Initial imaging demonstrated a rim-enhancing lesion within the left buccal space with no muscle invasion or bony erosion present. Two years later, imaging identified an enlarging buccal mass with destruction of the zygomatic arch and inferolateral orbital wall. The patient underwent surgical resection of the mass. Pathology confirmed the mass to be a small round blue cell tumor and FISH testing confirmed the presence of the EWSR1 gene arrangement that is consistent with EES. The patient tolerated the procedure well and underwent chemoradiation therapy. At three years postoperatively, the patient remains disease free. The presented case demonstrates an unusual presentation of a buccal space EES as a rim-enhancing, centrally hypointense mass with no bony erosion or muscular invasion. The location and atypical imaging appearance of this case offer insight for future diagnosis of EES.