4b (Spine) - Answer: 60-year-old male presents with low radiating back pain

History: This 60-year-old male presents with low back pain radiating to the anterior thigh and anterior calf within the last 6-8 months with no known injury.


Liposarcoma round cell variant

Using the diagnostic web viewer, we have provided images that assist in telling our clinical story. Areas of significance are indicated below.


Large heterogeneous left-sided pelvic mass within the left iliacus extending into and partially replacing the left psoas which measures 12.6cm superior to inferior, 13cm anterior to posterior, 8cm transverse. Hyperintensities within the lesion could represent hemorrhage. Lesion extends to the left ilium without abnormal signal within the ilium or evidence of left ilium or sacral bone destruction. Lesion extends distal to the foramina at L3,4, L4-5, L5-S1 without intraforaminal extension or widening. Left iliac vessel appears to be medially displaced by the lesion.   

Conus medullaris terminates at T12-L1.      

Subcutaneous edema may be of frictional origin.     

No acute sacral fractures.     

No acute microtrabecular stress reaction.   

L1-2: No canal or foraminal stenosis.   

L2-3: Bilobed disc displacement. Ligamentum flavum hypertrophy.   

L3-4: Facet arthropathy, disc desiccation, spondylosis. Broad central and right slightly inferiorly migrated disc protrusion effaces the right L4 root within the right lateral recess. Abutment of the left L4 root within the left lateral recess. Mild right foraminal stenosis.   

L4-5: Facet arthropathy, ligamentum flavum hypertrophy. Broad disc protrusion. Moderate central canal and lateral recess stenosis with L5 root effacement within the lateral recesses, L4 root abutment within the root foramina.  

L5-S1: Facet arthropathy. No canal or foraminal stenosis.   



Large heterogeneous possibly hemorrhagic mass within the left iliacus muscle extending into and partially replacing the left psoas muscle. Lesion extends to the outlet of the L3-4, L4-L5 and L5-S1 root foramina without intraforaminal extension or widening. Iliac vessels appear to be deviated medially. Lesion extends to the left ilium without bony destruction or expansion. Differential could include large soft tissue sarcoma. Dedicated MRI of the pelvis with and without contrast and consideration of tissue sampling is recommended.   

Examination was reviewed in neuro conference. Possible bony involvement of the left anterior ilium may be present on axial T2 series. Differential was discussed in neuro conference group. Additional differential consideration of soft tissue Ewing's, liposarcoma, malignant fibrous histiocytoma, fibro sarcoma and giant cell form of MFH.   

Findings were discussed. Issues discussed included the presence of a large pelvic mass, dimensions of the lesion and anatomic extension as well as differential were discussed. Further recommendation for imaging and tissue sampling were also discussed.


Upon further assessment, diffuse infiltration of the proximal ilium is noted consistent with the lesion's aggressive behavior pattern and size and supporting the diagnosis of a sarcoma with hemorrhage.

  Neuro MRI
  Body MRI