As neuroblastic tumors (neuroblastoma), Ewing sarcoma and primitive neuroectodermal tumors (PNETs) are closely related neoplasms supposedly derived from the neural crest.

Types

 Ewing sarcoma
 pPNET (peripheral primitive neuroectodermal tumors)

Variants

 "adamantinoma-like" variant
 spindled variant
 sclerosing variant
 clear cell variant
 anaplastic variant
 neuroendocrine variant

Cytogenetics and molecular biology

 22q12 reaarangements (EWS or EWSR1)

• t(11;22)(q24;q12) (EWSR1/FLI1 fusion gene) (90-95%)
• t(21;22)(q22;q12) (EWSR1/ERG fusion gene) (5-10%)
• t(2;22)(q33;q12) (EWSR1/FEV fusion gene)
• t(2;11;22)(q33;q24;q12)
• t(7;22)(p22;q12) (EWSR1/ETV1 fusion gene)
• t(17;22)(q21;q12) (EWSR1/ETV4 fusion gene)

 t(16;21)(p11;q22) (FUS/ERG fusion gene) (#1290763#)
 variant translocations involving a third chromosome: 4q21, 5q31, 6p21, 7q12, 10p11.2, 12q14, 14q11, 18p23

 chromosomal insertions

• 22q12 insertion in Chr.21 or Chr.11
• 21q21-q22 insertion in 22q12 (#15899394#)

 secondary chromosomal changes (50%)

• 8+
• 12+
• unbalanced tranlocations involving Chr.1 or Chr.16
• 1p- 1p deletion