Malignant or borderline mucinous cystic neoplasms have a larger number of loculi than mucinous cystadenoma: a retrospective study with MR.

PURPOSE: To determine whether there is any correlation between the number of loculi and the pathological grade of malignancy in mucinous cystic tumors of the ovary.

MATERIALS AND METHODS: We retrospectively studied MR images of 67 pathologically proven mucinous cystic tumors of the ovaries. Of these 67 cases, 38 were cystadenomas and 29 were malignant lesions (18 borderline malignancy and 11 adenocarcinomas). We counted the number of loculi and measured the maximum diameter of masses on MRI. We compared the number, the maximum diameter, and the ratio of the number of loculi to the maximum diameter in each adenoma and malignancy using Student's t-test.

RESULTS: The mean number of loculi was 18.2 in cystadenoma and 80.9 in malignant lesions. The mean maximum diameter of tumors was 13.0 cm in cystadenoma and 18.7 cm in malignant lesions. The mean ratio of the number of loculi to the maximum diameter was 1.3 in adenoma and 5.4 in malignant lesions. The differences between the benign and malignant lesions were statistically significant in number (P = 0.001), maximum diameter (P = 0.011), and ratio (P = 0.002).

CONCLUSION: Ovarian mucinous neoplasm of borderline malignancy and mucinous adenocarcinomas had a larger number of loculi than adenomas.