Fibrolipomatous hamartoma of the median nerve on CT

Fibrolipomatous hamartomas are rare lesions with a pathognomonic appearance on MRI. I describe CT findings that parallel the pathognomonic description on MRI. While these lesions are typically evaluated on MRI, they may be discovered incidentally on a CT scan of the upper extremity. In addition, contraindications to MRI may require CT evaluation in some cases. The findings of soft tissue with components of isointense fatty signal splaying out the nerve fascicles described as pathognomonic on MRI may also be applied on CT. While there is no surgical pathology of the lesion in this case, these lesions are not typically treated surgically. The pathognomonic findings on MRI can also be reproduced reliably on CT. Knowledge of these findings on CT can prevent unnecessary biopsy.