The value of the "ovarian crescent sign" to exclude an invasive malignancy.

Aim To examine the value of the “ovarian crescent sign” - a rim of normal ovarian tissue adjacent to an ipsilateral adnexal mass - as a sonographic feature to exclude an invasive malignancy. Methods During the IOTA phase 2 study, patients with an adnexal mass were included in 19 different international centers. All patients were scanned following the same standardized ultrasound protocol. The primary outcome was the histological diagnosis. More than 40 demographic and ultrasound variables were mandatory, but the evaluation of the “ovarian crescent sign” was optional. The ovarian crescent sign is assumed to exclude an invasive malignancy, therefore benign and borderline tumors were analyzed as one group. Results 1940 patients were included but the “ovarian crescent sign” was evaluated only in 1476 cases (76%) of which 1016 (69%) were benign and 460 (31%) malignant: 319 masses (21.6%) were primary invasive, 92 (6.2%) borderline and 49 (3.3%) metastatic. The “ovarian crescent sign” was present in 464 masses (425 benign, 20 primary invasive, 17 borderline, 2 metastasis). 299 (94%) of the primary invasive masses had no ovarian crescent sign, but in 20 cases (6%) it was reported: 13 epithelial carcinomas (3 stage I, 1 stage II, 8 stage III, 1 stage IV), 3 rare malignancies (struma, teratoma, GCT) and 4 extra ovarian malignancies (2 tubal ca, 1 clear cell ca of the uterus and one peritoneal ca with normal ovaries). The sensitivity and specificity for absence of the “ovarian crescent sign” to detect an invasive malignancy was 94.0% and 39.9%, LR + was 1.56 and LR − 0.15. Conclusion This study confirms previous reports that in the presence of the “ovarian crescent sign” the risk of an invasive malignancy is low. As a single ultrasound variable it can not reliably discriminate between benign and malignant adnexal masses but in combination with other ultrasound variables it might prove to be valuable. This far no scoring system or mathematical model has used it as a variable.