Utility of the “floating ball sign” in diagnosis of ovarian cystic teratoma

Objective: To evaluate the incidence of the “floating ball” sign in cross-sectional imaging modalities in patients with ovarian teratoma, and to investigate the relationship between the morphologic features of the teratoma and this sign. Materials and Methods: Preoperative computed tomography and magnetic resonance imaging studies of 112 women with a pathologic diagnosis of ovarian mature cystic teratoma (MCT) were reviewed for the presence of the floating ball sign. Tumor size, tumor characteristics and the number, size, and characteristics of floating globules were evaluated. Results: In 112 patients (mean age 35.5±16 years, range 5-84 years), 118 ovarian MCTs were diagnosed pathologically. The floating ball sign was demonstrated in cross-sectional imaging in 30 (25.4%) patients. Among 2 of them, MCT was associated with malignancy (squamous cell carcinoma). There was a significant relationship between the floating ball sign, tumor size, and the wall thickness of the tumor (p=0.003 and p=0.018, respectively). In linear regression analysis, a similarly significant relationship was found between the presence of this sign and tumor size and patient age (p=0.003 and p=0.035, respectively). Conclusion: The floating ball sign, as a pathognomonic sign for the diagnosis of ovarian teratomas, seems to be more common than is known. Although this sign is almost always seen in MCTs, it may rarely be seen in teratomas with malignant transformation. The relationship of this sign with the characteristics of the tumor can provide an insight into the occurrence of these balls.