Ewing's Sarcoma Diagnosis and Management

Initial Diagnostic Evaluation

The European Society for Medical Oncology recommends that patients with radiological findings suggesting Ewing's sarcoma should be immediately referred to a specialized bone sarcoma center for proper diagnosis and management without prior biopsy 1, 2, 3
A complete radiological assessment of the entire affected bone should be performed before any biopsy, as recommended by the European Society for Medical Oncology 1, 2, 3
Histological diagnosis is made by needle biopsy or open surgical biopsy at a specialized center, according to the European Society for Medical Oncology 1, 2
Ewing's sarcoma can be distinguished from other pediatric "blue tumors" by expression of the MIC2 gene, as noted by the European Society for Medical Oncology 1, 2
Molecular testing, including detection of characteristic translocations involving the EWS gene, is diagnostic and present in >90% of cases, as recommended by the European Society for Medical Oncology 1, 2

Computed tomography of the chest should be performed to detect lung metastases, as recommended by the European Society for Medical Oncology 1, 2, 4
Bone scintigraphy should be used to investigate potential bone metastases, according to the European Society for Medical Oncology 1, 2, 4
Bone marrow aspirates are mandatory for light microscopy examination, as noted by the European Society for Medical Oncology 1, 2, 3
Sperm banking should be considered before initiating treatment, as recommended by the European Society for Medical Oncology 1, 2
Approximately 20% of patients have detectable metastases at diagnosis, most commonly in lungs and/or bone/bone marrow, according to the European Society for Medical Oncology 1, 2, 3

Tumor size should be documented, with diameters >8-10 cm indicating worse prognosis, as noted by the European Society for Medical Oncology 1, 2, 4
Tumor location should be noted, with pelvic region tumors indicating worse prognosis, according to the European Society for Medical Oncology 1, 2, 4
Patient age should be documented, with ages >15 years indicating worse prognosis, as recommended by the European Society for Medical Oncology 1, 2, 4
Serum lactate dehydrogenase levels should be measured, with elevated levels indicating worse prognosis, according to the European Society for Medical Oncology 1, 2, 4

Treatment should be coordinated by a specialized center with expertise in Ewing's sarcoma, as recommended by the European Society for Medical Oncology 1, 5, 4
Combination chemotherapy including doxorubicin, vincristine, ifosfamide, etoposide, dactinomycin, and cyclophosphamide should be prepared, according to the European Society for Medical Oncology 1, 5, 4
Local therapy assessment should evaluate feasibility of surgery versus radiotherapy based on tumor location and extent, as noted by the European Society for Medical Oncology 1, 5, 6
Histological response to preoperative chemotherapy should be assessed, as recommended by the European Society for Medical Oncology 1, 5, 4

Delayed referral to specialized centers can lead to contamination of tissue planes and compromise subsequent surgical management, as noted by the European Society for Medical Oncology 1, 2
Inadequate staging can lead to inappropriate treatment planning, according to the European Society for Medical Oncology 1, 2, 3
Improper biopsy technique can compromise subsequent surgical management, as recommended by the European Society for Medical Oncology 1, 2
Underestimating the importance of molecular diagnosis can lead to inaccurate diagnosis, according to the European Society for Medical Oncology 1, 2

MRI is the most accurate radiological method for diagnosing, staging, and monitoring Ewing's sarcoma, and should be repeated after chemotherapy and definitive local therapy to evaluate treatment response 7, 8
Plain radiographs in two planes are the essential first-line imaging study and typically reveal findings indicative of malignant tumor 9
CT of the chest is mandatory for detecting lung and pleural metastases, which occur in approximately 10% of patients at diagnosis 9
MRI provides the most accurate evaluation of local tumor extent, including bone marrow involvement, soft tissue extension, and relationship to neurovascular structures 7, 8, 9
The entire involved bone must be imaged with MRI before biopsy to avoid contaminating tissue planes 9

The same radiological method used for initial staging should be repeated after chemotherapy to assess response 7, 8
MRI should be repeated after neoadjuvant chemotherapy to assess treatment response, looking for changes in signal intensity, decreased extent of abnormal marrow signal, and reduction in soft tissue mass 7, 8

Complete radiological staging requires plain radiographs of the primary site in two planes 9
Complete radiological staging requires MRI of the entire involved bone for local staging 9
Complete radiological staging requires CT chest for pulmonary metastases 9
Complete radiological staging requires 99mTc bone scintigraphy for skeletal metastases 9
99mTc bone scintigraphy is required to detect osseous metastases, which occur in approximately 10% of patients at diagnosis 9
PET scanning for bone metastases is currently under evaluation but not yet standard of care 9