dr james c wittig, orthopedic oncologist, new york, new jersey
Patient Education
Extraskeletal Ewing Sarcoma

GENERAL INFORMATION

Extraskeletal Ewing Sarcoma (EES) is a malignant small round-blue cell tumor than arises most often in Children and adolescents. Tefft et al in 1969 described the first series of Extraskeletal Ewing Sarcoma that arose from the paravertebral soft tissues. Ewing sarcoma, although a rare type of sarcoma,  is most typically a type of sarcoma that arises from bone. However more rarely Ewing Sarcoma can arise from the soft tissues and is then termed Extraskeletal Ewing Sarcoma.  EES is a rare tumor composed of monotonous primitive small round blue-celsl distributed in pieces or lobules. It’s has an annual incidence rate of 1-3 cases per million. Ewing sarcoma and primitive neuroectodermal (PNET) tumor fall in the same family of tumors. 

CLINICAL DATA

High grade sarcoma
Rare soft tissue tumor, indistinguishable from 

Ewing sarcoma of bone
Usually affects patients age 30 or less, occasionally age >50
Slight male preference
Most commonly metastasizes to lung and bones

DIFFERENTIAL DIAGNOSIS
Lymphoma
Rhabdomyosarcoma
Infection/abscess

CLINICAL PRESENTATION

Sign/Symptoms
Usually a large and deep mass
Rarely subcutaneous
Rapidly growing
Usually painless (pain in 30% of cases)

Prevalence
Much less common than skeletal Ewing sarcoma
Slight predilection for males
Rarely effects afro-americans
Occurs in all ages but usually younger population
Preference for individuals between 15 and 40 years

Site
Commonly in soft tissue of lower extremities and thorax


RADIOGRAPHIC PRESENTATION

Plain x-ray
No specific radiological features
May reveal a soft tissue mass
No mineralization
If adjacent to a bone may show underlying bony erosion

CT
Shows attenuation similar to the muscle
May be heterogenous with areas of necrosis and hemorrhage

MRI
Low to intermediate signal intensity on T1W
High signal intensity on T2W
Usually heterogeneous from necrosis and hemorrhage



Fig. 1



Fig. 2

Fig. 1-2 Axial (Fig. 1) and coronal CT (Fig. 2) reconstruction of the femur and thigh shows an Extraskeletal Ewing Sarcoma arising in the soft tissues adjacent to the femur



Fig. 3



Fig. 4

Fig. 3-4 Axial (Fig. 3) and coronal (Fig. 4) T1 W MRI of the thigh shows an Extraskeletal Ewing Sarcoma that is iso-intense with the adjacent musculature.




Fig. 5



Fig. 6

Fig.  5-6 Axial (Fig. 5) and coronal (Fig. 6)T1 post contrast MRI shows a  heterogenous mass with enhancement post contrast 




Fig. 7 



Fig. 8

Fig. 7-8 Axial (Fig. 7) and coronal (Fig. 8) T2W shows heterogenous high signal intensity

PATHOLOGY



Fig. 9



Fig. 10

Fig. 9-10 Microscopic:  Low power (Fig. 9) and high power (Fig. 10) views of an Extraskeletal Ewing Sarcoma shows a monotonous Collectionb of small round blue cells. The cells have large nuclei and minimal cytoplasm.

IMMUNOHISTOCHEMISTRY

Positive
o CD 99
o PSA
o Vimentin
Negative
o S-100
o NF
o CK 7
o CK 19
o Leukocyte antigen


PROGNOSIS

Biological Behavior

Tumor cells often express MIC2 gene
o Demonstrate several novel reciprocal chromosomal translocations and fusion gene transcripts
o t(11;22) chromosomal translocation most commonly encountered and often aides in diagnosis

High rate of metastasis
o Most commonly in the lungs and bones
Best prognosis in patients age<16 years who underwent surgical resection and chemotherapy.
Patients with metastatic disease generally die within 2 years
50% 5-years survival rate in patients who present with localized disease

TREATMENT

Complete excision; Limb Sparing Surgery
Radiotherapy may be indicated
Multi-drug chemotherapy (cyclophospphamide, ifosfamide, etoposide, doxorubicin and vincristine)
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