MR Imaging Findings of Ovarian Cystadenofibroma: Clues for Making the Differential Diagnosis from Ovarian Malignancy

varian cystadenofibromas are uncommon epithelial ovarian tumors in which fibrous stroma is the dominant component of the neoplasm, in addition to the epithelial lining of the cystic tumor. These tumors are classified, according to the epithe-lial cell types, into the serous, endometrioid, mucinous, clear cell and mixed categories. The degree of epithelial proliferation and its relation to the stromal component of the tumor are used for their classification as benign, borderline and malignant tumors, although most of the reported ovarian cystadenofibromas were usually benign (1 3). There are a few reports that have described the MR imaging features of ovarian cystadenofibromas (3 7). In their reports, the gross morphology of ovarian cystadenofi-bromas was predominantly cystic and the most frequent finding was the presence of solid nodules. Outwater et al. (3) have reported that ovarian cystadenofibromas were multilocular cystic masses with a solid component and they had a specific MR signal intensity for the solid portion, which consisted of fibrous tissue that had very low signal intensity on the T2-weighted sequences. Takeuchi et al. (5) reported that small or tiny cystic locules within the solid component are the characteristic findings of cystadenofi-broma, corresponding to a black sponge-like appearance on T2-weignted image. Cho et al. (7) found that about half of ovarian cystadenofibromas are purely cystic and the other half are complex cystic masses with one or more solid components on CT or MR imaging. The imaging findings of purely cystic ovarian cystadenofibromas were identical to those of ovarian cystadenomas on CT or MR imaging (8). Upon reviewing of the pathology of these tumors, they had small foci of fibrous stromas that were detected only on microscopic examination. The cystade-nofibromas with a complex cystic nature demonstrated variable amounts of solid components in the cystic tumor on the CT or MR imaging. Due to their solid component or thick septa, they were all diagnosed as being malignant on the preoperative imaging (7). The article by Jung et al. (9) in this issue of the Korean Journal of Radiology has reported other common imaging features of ovarian cystadenofibromas on MR imaging. They encountered several cases of cystadenofibroma that showed different MR imaging findings from the previous characteristic findings. The previously reported characteristic MR findings of cystadenofibroma (a multilocular cystic mass with a T2-dark-signal-intensity solid component containing small cystic locules) were found only in 43% of the tumors they examined. Diffuse or partial thickening of …