Presentation
Pelvic pain for the past 3 months.
Patient Data
There is a lytic lesion involving the left S1 vertebral body, sacral ala and body with bony destruction and spinal extension. There is no associated sclerosis.
The left-sided sacroiliac joint is unremarkable.
Lytic expansile multiloculated heterogenous signal enhancing mass with soft tissue component at the S1 vertebral body and left pedicle as well as the left sacral blade is seen due to bone marrow infiltration.
Extracanalicular extension of the soft tissue component through the left neural foraminal and compressing the nerve roots.
Pelvic cavity soft tissue extension deep to the iliopsoas muscle also is noted.
Case Discussion
Cytogenesis:
Positive for EWSRI (22q12) gene rearrangement by FISH.