There are no universally accepted criteria for distinguishing between benign and malignant ovarian masses on the basis of ultrasound findings. Risk of malignancy indices have been proposed, but these methods use complex calculations and study multiple parameters to develop a score. The detection of normal ovarian tissue in the adnexal masses, the ovarian crescent sign, is highlighted as a single ultrasound parameter prejudging the nature of adnexal mass as benign or malignant. It has been reported that absence of the “ovarian crescent sign” is a more sensitive indicator of malignant nature than the risk of malignancy indices.
To evaluate whether the presence of normal ovarian tissue adjacent to adnexal masses (the ‘ovarian crescent sign’) could assist in the preoperative differential diagnosis of these masses, and to compare its accuracy with standard biochemical and sonographic indices.
Sixty four women with adnexal masses were included in this prospective observational study. Serum cancer antigen 125 levels were measured and transvaginal and/or transabdominal ultrasound scans of the adnexae were performed and the tissue adjacent to the mass was examined for the presence of the ‘ovarian crescent sign’. The risk of malignancy index was calculated and all the findings were compared with the final histopathological diagnosis and the accuracy of each test was compared to the others in the form of sensitivity, specificity, positive and negative predictive values.
Fifty five out of sixty four women were found to have benign masses, one had a borderline tumor and eight had invasive malignant lesions. Normal ovarian tissue ‘ovarian crescent sign’ was seen in fifty three out of fifty five women with benign lesions but it was not seen in any one of the nine women with malignant lesions.
In the absence of the “ovarian crescent sign”, ovarian cancer was diagnosed with a sensitivity of 100% and a specificity of 96.4%. For the cancer antigen 125 test, the sensitivity was found to be 77.7%, specificity 92.7%; for the Risk of Malignancy Index, sensitivity was 55.6% and specificity was 89.1%.
The “ovarian crescent” sign is a reliable sonomorphological feature that can help to exclude ovarian cancer in patients with adnexal masses, while its absence highly indicates malignancy.