Torsion of Ovarian Teratoma

Fig. 1 Transverse ultrasound of the pelvis in a 26-year-old woman presenting with RLQ pain. There is a midline pelvic mass with homogeneous high echogenicity (red arrows) and some posterior acoustic shadowing (blue stars). 
Fig. 2 Axial CT image shows a midline mass (red arrows) containing fat, soft tissue and bone (yellow arrow), consistent with an ovarian teratoma. There was no specific sign of torsion presented. Color Doppler flow was normal within the mass. Only hint of torsion is the midline position of the mass itself. Surgery confirmed torsion.

Facts:

• Torsion is the most common complication of ovarian teratoma (16%).
  
• Most common mass associated with torsion is ovarian teratoma.
  
• Characteristic feature of ovarian teratoma is fat in the mass.
• Most specific signs (not present in this case) for torsion are thickening of fallopian tube (CT) and 'whirling' of vascular pedicle (US, CT)

Reference:

Park, et al. Radiographics 2008;28:969-983. (Jul-Aug)