Ewing's sarcoma

Ewing sarcomas
Micrograph of metastatic Ewing sarcoma (right of image) in normal lung (left of image). PAS stain.
Classification and external resources
Specialty	Oncology
ICD-10	C41.9
ICD-9-CM	170.9
ICD-O	M9260/3
OMIM	612219
DiseasesDB	4604
MedlinePlus	001302
eMedicine	ped/2589
MeSH	D012512
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Ewing's sarcoma or Ewing sarcoma (/ˈjuːɪŋ/) is a malignant small, round, blue cell tumor. It is a rare disease in which cancer cells are found in the bone or in soft tissue. The most common areas in which it occurs are the pelvis, the femur, the humerus, the ribs and clavicle (collar bone).

Since a common genetic locus is responsible for a large percentage of Ewing's sarcoma and primitive neuroectodermal tumors, these are sometimes grouped together in a category known as the Ewing family of tumors. The diseases are, however, considered to be different: peripheral primitive neuroectodermal tumours are generally not associated with bones, while Ewing sarcomas are most commonly related to bone.

Ewing's sarcoma occurs most frequently in teenagers and young adults, with a male/female ratio of 1.6:1.

Although usually classified as a bone tumour, Ewing's sarcoma can have characteristics of both mesodermal and ectodermal origin, making it difficult to classify.

James Ewing (1866–1943) first described the tumour, establishing that the disease was separate from lymphoma and other types of cancer known at that time.

Genetic exchange between chromosomes can cause cells to become cancerous. Most cases of Ewing's sarcoma (85%) are the result of a translocation between chromosomes 11 and 22, which fuses the EWS gene of chromosome 22 to the FLI1 gene of chromosome 11.

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