Fibrothecomas of the ovary: CT and US findings.

Objective: Fibrothecomas of the ovary are mesenchymal tumors representing 4-5% of all ovarian neoplasms. The purpose of this study is to describe a large series of CT findings in this type of tumor.
Materials and Methods: We reviewed retrospectively the CT examinations in 25 unilateral cases confirmed by surgery and pathology. Unenhanced and enhanced CT scans were performed in all cases and dynamic CT scans were performed in nine cases. These findings were compared to ultrasound in all cases.
Results: Computed tomography detected all but two small ovarian tumors (< 2 cm). Eighteen of 23 fibrothecomas were solid, with significant (> 10 HU) enhancement between precontrast and delayed CT scans. In all eight uncomplicated cases, nonincremental dynamic CT scan did not visualize arterial vessels; in seven of nine cases examined dynamically, early uptake of contrast material was visualized. Three of 23 fibrothecomas were partly cystic, partly solid. Two cases with torsion were mainly cystic with thickening and hemorrhage of the tube.
Conclusion: In conclusion, 79% of ovarian fibrothecomas appeared as solid masses with delayed accumulation of contrast medium. On dynamic CT, the absence of arterial vessels and absence or slight early uptake of contrast enhancement could be useful findings for preoperative diagnosis. When partly or mainly cystic (21% of cases), ovarian fibrothecomas could not be easily differentiated from other ovarian masses.