Primary Ewing sarcoma of lumbar spine with massive intraspinal extension.

Primary vertebral Ewing sarcoma-primitive neuroectodermal tumor is uncommon. Although epidural extension has been seen in such tumors, cases with massive intraspinal involvement are decidedly rare. Here we present the case of a 4-year-old girl with back pain and difficulty walking. Magnetic resonance imaging showed a mass filling the spinal canal from T(11) to the L(3)/L(4) levels. Vertebral involvement with extension into the paraspinal soft tissue through neural foramina was seen. Histologically, a small-blue-cell tumor with strong membranous CD99 reactivity was noted. Molecular analysis revealed translocation t(11;22)(q24;q12), thus confirming the diagnosis of Ewing sarcoma-primitive neuroectodermal tumor. Our case emphasizes that vertebral Ewing sarcoma-primitive neuroectodermal tumor may present with massive intraspinal extension and should be included in the differential diagnosis of intraspinal lesions.