Cáceres Corner Case 236 – Vignette

Dear Friends,

Today’s radiographs belong to a 65-year-old woman with back pain. She was operated for myxoid liposarcoma of the lower limb seven years ago.

Do you see any abnormality?
If so, where is it?

1. Upper area
2. Middle area
3. Lower area
4. I don’t see it

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Findings: PA radiograph shows a double contour of the aortic knob (A, arrow) which indicates a superimposed mediastinal mass either in front or behind the knob. Lateral view shows increased opacity of the upper thoracic spine (B, circle), suggesting a posterior mass.

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Unenhanced CT was done. What would be your diagnosis?

1. Neurogenic tumor
2. Metastasis
3. Neurenteric cyst
4. Any of the above

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Findings: coronal and axial unenhanced CT show a posterior mediastinal mass (C-D, arrows). Of the three possible diagnosis, I would choose neurogenic tumor/cyst, because they are frequent in the posterior mediastinum.

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MRI was done. Would you change your diagnosis?

1. Neurogenic tumor
2. Metastasis
3. Neurenteric cyst
4. Any of the above

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Findings: MRI discovers that the vertebral body is affected (E-F, arrows). This makes neurogenic tumor unlikely. There are visible vessels within the mass, which excludes a cyst. Since myxoid liposarcomas metastasize to the spine, the best possibility is metastasis.
At surgery, a metastatic focus from liposarcoma was found.

Final diagnosis: Metastasis from liposarcoma

This is an interesting case because in the PA radiograph the abnormality is partially hidden by the aortic knob and can be difficult to see (remember to use checklists!).

As a chest radiologist occupying the lower strata of the totem pole, I confess my profound ignorance of liposarcomas. Surfing the Internet I have discovered several papers that state that myxoid liposarcoma metastasizes frequently to the spine and that MRI is the method of choice to demonstrate vertebral metastases in these cases.
Now I can transmit my new-found knowledge to you.

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