Musculoskeletal case 13. Presentation
=====================================

* William C. Torreggiani
* Peter L. Munk
* Kalid al-Ismail
* Mark J. Lee

A 55-year-old woman was referred to the surgical outpatient department for the evaluation of a palpable bulge over the left part of her back, associated with mild pain. She had initially noticed the lump about a year before but had only recently decided to seek medical advice. She had not noticed any significant change in the size of the lump during the year. There was no relevant medical or surgical history, and she was not taking any medications.

On physical examination there was a palpable bulge over the left paraspinal area. However, no distinct underlying mass could be palpated. There were no other abnormalities. She was referred to the Department of Radiology for further assessment by computed tomography and magnetic resonance imaging. From the contrast enhanced CT scan (Figs. 1 and 2) and the transverse *T*2-weighted MR image (Fig. 3) and gradient coronal MR image (Fig. 4), what is the most likely diagnosis?

![FIG. 1](http://canjsurg.ca/https://www.canjsurg.ca/content/cjs/43/6/409/F1.medium.gif)

[FIG. 1](http://canjsurg.ca/content/43/6/409/F1)

FIG. 1 

![FIG. 2](http://canjsurg.ca/https://www.canjsurg.ca/content/cjs/43/6/409/F2.medium.gif)

[FIG. 2](http://canjsurg.ca/content/43/6/409/F2)

FIG. 2 

![FIG. 3](http://canjsurg.ca/https://www.canjsurg.ca/content/cjs/43/6/409/F3.medium.gif)

[FIG. 3](http://canjsurg.ca/content/43/6/409/F3)

FIG. 3 

![FIG. 4](http://canjsurg.ca/https://www.canjsurg.ca/content/cjs/43/6/409/F4.medium.gif)

[FIG. 4](http://canjsurg.ca/content/43/6/409/F4)

FIG. 4 

For the answer see page 466.

## Footnotes

*   Inquiries about this section should be directed to the section editor, Dr. Peter L. Munk, Professor, Department of Radiology, Vancouver General Hospital, Vancouver Hospital and Health Sciences Centre, 855 West 12th Ave., Vancouver BC V5Z 1M9.