Musculoskeletal case 24. Presentation
=====================================

* Ciaran Keogh
* William C. Torreggiani
* Khalid Al-Ismail
* Peter L. Munk

A 20-year-old man was referred to the Department of Radiology for evaluation of a lump he had noticed in his right upper extremity 6 months earlier. Clinical examination confirmed the presence of an illdefined nontender mass in the region of the deltoid muscle. The rest of the clinical examination showed no abnormalities. Initial plain radiographs were normal. He subsequently underwent computed tomography and magnetic resonance imaging. Fig. 1 is a representative axial (transverse) CT image through the deltoid muscle. Fig. 2 is a representative *T*1-weighted coronal oblique magnetic resonance image through the abnormal area.

![FIG 1](http://canjsurg.ca/https://www.canjsurg.ca/content/cjs/45/5/367/F1.medium.gif)

[FIG 1](http://canjsurg.ca/content/45/5/367/F1)

FIG 1 

![FIG 2](http://canjsurg.ca/https://www.canjsurg.ca/content/cjs/45/5/367/F2.medium.gif)

[FIG 2](http://canjsurg.ca/content/45/5/367/F2)

FIG 2 

What is your diagnosis?

For the answer and a discussion see page 389.

## Footnotes

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