Ewing’s sarcoma is a peripheral primitive neuroectodermal tumour .
Epidemiology :
Age distribution – 10 to 25 years
Male : Female = 2 : 1
Locations: 50% in long tubular bones (commonest in lower extremities – diaphysis) . 40% in flat bones – innominate portion of the pelvis is most commonly affected . Scapula , spine (sacrum and lumbar spine) , ribs .
Genetics: t(11;22)
Pathology : Undifferentiated sheets of small round cells (to distinguish from non-Hodgkin’s lymphoma – PAS staining for glycogen granules .
Cell surface marker for peripheral PNET – p 30/32 ; product of mic – 2 gene .
Clinical features:
Local pain with swelling . Fever , anaemia , leukocytosis increased ESR . Local temperature elevation and tenderness (signs of inflammation).
X - rays: Permeative destruction with a wide zone of transition. Onion peel periosteal reaction. 1/3rd of cases affecting flat bones demonstrate diffuse sclerosis (normal bone formed as a reaction to tumour cells)
CT/MRI – generous soft tissue mass
Metastases : Spine , lung parenchyma and pleura , bone marrow .
5 years survival rate – 5%
Treatment : Chemotherapy + radiotherapy
Ewing sarcoma is a curable tumour even in the presence of obvious metastatic disease especially in children <11 years .