Lipoleiomyoma

CT shows a predominantly fat attenuation, intramural uterine mass. There is rim of surrounding calcification as well as a few foci of internal soft tissue density at the superior aspect of the mass 

   MR imaging showed the majority of the uterine mass as hyperintense on T1 weighted imaging (isointense to subcutaneous fat)

T2 weighted image with fat saturation MRI shows the uterine mass markedly hypointense (isointense to subcutaneous fat)

Post contrast T1 weighted MRI image with fat saturation show mld enhancement of the soft tissue component  along the superior margin of the mass; the majority of the mass is markedly hypointense (isointense to subcutaneous fat)

Uterine lipoleiomyomas are rare, benign tumors with a variable reported incidence ranging from 0.03% to 0.2%. The exact etiology of these lesions is unclear.  It is postulated lipoleiomyomas either arise from fatty metaplasia of the smooth muscle cells of leiomyomas, or from misplaced embryonic fat cells in the uterus. CT is highly specific for the diagnosis when an intrauterine mass is seen containing both macroscopic fat and soft tissue density. MR can also be confirmatory as the mass will have high T1 weighted signal which can be confirmed as fat by using a fat suppression. The role of imaging is also to differentiate lipoleiomyoma from an ovarian teratoma, a much more common entity presenting as a fat-containing pelvic mass. Lipoleiomyomas require no treatment or follow-up whereas teratomas are frequently resected. 

References

• Preito A,Crespo C, Pardo A, Docal I, Calzada J, Alonso P. Uterine lipoleiomyomas: US andCT findings. Abdom Imaging 2000;25:655-7
• MaebayashiT, Imai K, Takekawa Y, et al. Radiologic features of uterine lipoleiomyoma. JComput Assist Tomogr 2003;27:162-5
• AvritscherR, Iyer RB, Ro J, Whitman G. Lipoleiomyoma of the uterus. AJR Am J Roentgenol2001;177:856
• Dodd GD III,Budzik RF. Lipomatous uterine tumors: diagnosis by ultrasound, CT, and MR. JComput Assist Tomogr 1990;14:629-32