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24 yo male with lower extremity progressing weakness

Differential Diagnosis

Ewing Sarcoma

Permeative lesion of vertebral body.

May involve adjacent vertebrae without disc height loss or peridiscal erosions

Primitive Neuroectodermal tumor

Radiographically identical to Ewing sarcoma

Langerhans Cell Histiocystosis

May have identical features of Ewing sarcoma

Can form discrete geographic lytic lesions

Small Round cell tumors

Lymphoma, leukemia, myeloma, metastatic neuroblastoma

Tend to involve vertebral body more than neural arch

Osteomyelitis

Ill defined permeative lytic lesion

Involves vertebral body more than neural arch

Discocentric – extends from one vertebral body to adjacent across disc, disc height loss with endplate erosions, disc enhancement

Osteogenic Sarcoma

Ill defined lytic lesion with permeative pattern

80% show bone matrix on CT

Involves vertebral body or neural arch and may involve adjacent body

Ewing Sarcoma

A round cell sarcoma of bone

Spine -5% of all lesions (sacrum>spine)

Involve vertebral body before neural arch

May involve adjacent bones

Contiguous spread along peripheral nerves

May originate in soft tissues

Radiographic Findings

CT

Tiny perforations of cortex rather than extensive loss

Wide zone of transition permeative pattern

50% have extraosseous noncalcified soft tissue mass

Vertebra plana

If adjacent vertebrae involved do not typically see disc height loss or peridiscal erosions

MRI

T1

intermediate to low signal intensity

Cortex appears thinned but intact

T2

intermediate to high signal

Cannot reliably distinguish between tumor and peritumoral edema

STIR

hyperintense and better visualized than on T2

T1+c

enhancement, regions of necrosis, cannot reliably distinguish tumor from peritumoral edema

Pathology

Nonhematologic round cell tumor

Closely related to PNET

Undifferentiated mesenchymal cells with slight differentiation toward neuroectodermal cell.

Gray white tumor with areas of necrosis hemorrhage and cyst formation

Microscopic-small round cells 2-3x larger than lymphocytes, high mytotic rate, round nuclei with frequent indentations

FISH (Fluorescence in Situ Hybridization) utilized

Presentation

Age-90% present before age of 20 a second peak seen at 50 yrs of age

Annual incidence 3/1,000,000 Caucasian children less than 15 yo

Spine and sacral lesions often in older patients than peripheral lesions.

M:F=2:1

Presentation

Localized pain, fever, leukocytosis, radiculopathy to paralysis

Natural History/Treatment

Metastases to lung, regional lymph nodes, or other bones - 30% at presentation

Prognosis worse in spinal than peripheral Ewing sarcoma due to more difficult resection

Current treatments yield long term survival > 50% with localized disease

Treatment

Surgery with neoadjuvant chemotherapy prior to surgery