Fibrothecoma of the Ovary

Fibrothecomas are benign sex cord–stromal tumors of the ovary composed of various proportions of fibromas and lipid-rich, estrogenic thecomas. Fibrothecomas can occur in pre- and post-menopausal women and are the most common of the sex cord–stromal tumors.

On US, fibrothecomas usually appear as a homogeneous hypoechoic mass with posterior acoustic shadowing, but in most cases the appearance of the tumor is nonspecific. CT reveals a homogeneous solid tumor with delayed enhancement. Dense calcifications are often seen.

Fibrothecomas have low signal intensity on T1- and T2-weighted images, representing the fribous component. Scattered high-signal-intensity areas in the mass represent edema or cystic degeneration. In masses with cystic degeneration, the solid component is usually located peripherally.

Differential considerations include uterine leiomyomata and other ovarian masses with fibrous components (fibroma, cystadenofibroma, and Brenner tumor). Differentiation from uterine leiomyomata can be made by noting that ovarian masses are usually supplied by ovarian arteries or by the ovarian branches of the uterine arteries that course along the fallopian tubes. The presence of interface vessels between the uterus and the adnexal mass can help differentiate a uterine leiomyoma from an ovarian fibromous tumor.

The images above show a hypoechoic right adnexal mass. A cystic component (not shown) was also visualized. It was initially felt that the mass was contiguous with the uterus and represented a pedunculated leiomyoma; however, because the right ovary could not be seen on ultrasound, an ovarian mass was also considered, and an MRI performed. MRI showed a right ovarian mass with heterogeneous signal intensity on T2-weighted images and low signal intensity on T1-weighted images (pink arrow). A peripheral cystic component (c) was also seen. No enhancement was seen following contrast administration.

References

• Jung SE, Lee JM, Rha SE, Byun JY, Jung JI, Hahn ST. CT and MR imaging of ovarian tumors with emphasis on differential diagnosis. Radiographics. 2002 Nov-Dec;22(6):1305-25.
• Outwater EK, Wagner BJ, Mannion C, McLarney JK, Kim B. Sex cord-stromal and steroid cell tumors of the ovary. Radiographics. 1998 Nov-Dec;18(6):1523-46. Review.