Ewing's Sarcoma (Complete) Flashcards
Define Ewing’s sarcoma
Malignant small round-cell tumor primarily involving bone and soft tissue in some cases
Summarise the aetiology of Ewing’s sarcoma
Occurs due to chromosomal translocations ((e.g. t(11;22)(q24;q12)) resulting in EWS_FLI1 fusion gene.
Results in abnormal transcription factors which promote tumorgenesis
Ewing’s sarcoma is associated with translocation between which chromosomes?
11 and 22
T 11;22
Ewing’s sarcoma is common in which age groups?
Under 20 years
What percentage of bone sarcoma diagnoses in children/young adults are due to Ewing’s sarcoma
14%
Second most common bone sarcoma in younger population
What are the stages of Ewing’s sarcoma?
Stage 1A /1B
Stage 2 A/B
Stage 3
What are the diagnostic criteria for Ewing sarcoma stage 1A
Low-grade tumor
Restricted to hard bone
What are the diagnostic criteria for Ewing sarcoma stage 1B
Low-grade tumor
Restricted to local tissue
What are the diagnostic criteria for Ewing sarcoma stage 2A
High-grade tumor
Restricted to hard bone
What are the diagnostic criteria for Ewing sarcoma stage 2B
High-grade tumour
Extendes to local tissues
What are the diagnostic criteria for Ewing sarcoma stage 3?
Any low/high-grade tumour which has metastasised
What are the main features of Ewing’s sarcoma?
Palpable mass/swelling
- Located mainly on the long bones
- Occasionally, pelvis, ribs and vertebrae
Nocturnal bone pain
Restricted joint mobility
Systemic features
- Weight loss
- Night sweats
- Fever
What are the main investigations for patient’s with suspected Ewing’s sarcoma?
Bedside:
Basic obs: Fever, weight loss
Bloods:
FBC: Check for anaemia (poor prognostic marker)
LDH: High
ESR/CRP: Rule out osteomyelitis
LFT: ALP raised in osteosarcoma
Imaging:
X-ray: Within 48 hours for any patient with unxeplained bone swelling/pain
CT/MRI/PET: Visualise extent of disease
Bone biopsy: Definitive diagnosis
Which presentations warrant 48 hour urgent bone x-ray
Any patient with unexplained bone pain/swelling
What findings on X-ray are suggestive of Ewing’s sarcoma?
Onion skin appearance
Due to bone destruction with layers of periosteal bone formation.
What investigation provides a definitive diagnosis for Ewing’s sarcoma?
Bone biopsy
What histological findings on bone biopsy are suggestive of Ewing’s sarcoma?
Sheets of small round cells
CD99 +ve immunostaining
t11;22
What surface marker is highly specific for Ewing’s sarcoma?
CD99
What labaratory findings are associated with poor prognosis?
Anaemia
High LDH
What is the management plan for patients with Ewing’s sarcoma?
Medicine:
Chemotherapy (First-line): To reduce tumor size before surgery
Radiotherapy: As adjuvant or when surgery is not feasible
Surgical:
Surgical removal of primary tumor
What is the first-line management of Ewing’s sarcoma
Chemotherapy
What differentials should be considered alongside Ewing’s sarcoma?
Osteosarcoma
Osteomyelitis
Lymphoma
Osteoid osteoma
How can osteosarcoma be differentiated from Ewing’s sarcoma?
Mostly presents in the knee (60%) or metaphysis of bones versus (diaphysis) shaft of long bones.
Moresoe associated with pathological fractures versus systemic symptoms
High ALP due to increased osteoblastic activity
Sunburst appearance versus onion skin
Malignant mesenchymal cells versus small round cells
How can ostemyelitis be differentiated from Ewing’s sarcoma?
Subacute versus insidious presentation
High-grade versus low-grade fever
Raised inflammatory markers (e.g. WBC, ESR/CRP)
Positive blood cultures
Lytic lesions versus onion skin periosteal reaction
