November 17, 2014
A 60-year-old man with metastatic left tonsillar squamous cell cancer underwent a staging MRI neck and CT head examination.
Intraosseous Lipoma
- Intraosseous lipoma is a rare benign tumor: To date, only 13 cases have been reported to involve the sphenoid bone.
- Furthermore, accurate identification of this lesion is important to avoid surgery.
- Key Diagnostic Features:
- On MRI, this lesion shows signal characteristics of fat — ie, it is hyperintense — on T1WI and T2WI, signal drop on fat saturation sequence, and no enhancement following contrast administration.
- On CT, this lesion demonstrates fat attenuation with well defined bony margins.
- The tumor is divided into 3 stages:
- Stage I: Solid lesions demonstrate viable fat.
- Stage II: Transitional lesions contain regions of viable fat and fat necrosis, as well as areas of dystrophic calcification.
- Stage III: They show involutional changes with extensive fat necrosis, cyst formation, calcification, and reactive new bone formation.
- Likewise, they have variable CT and MRI appearances according to stage.
- Rx: Incidental finding
