Schematic showing classes of ovarian cysts and the diagnostic potential of the cyst fluid.Ovarian cysts and tumors are currently classified according to microscopic evaluation after surgical removal. The majority of ovarian cysts are non-neoplastic (often 'functional' in premenopausal women). Ovarian tumors with combined cystic and solid components are either benign tumors, borderline tumors, or malignant cancers (type I or II). Only cysts associated with borderline tumors and cancers require surgical excision. We show here that the DNA purified from cyst fluid can be analyzed for somatic mutations commonly found in their associated tumors. The type of mutation detected not only could indicate the type of tumor present but also could potentially inform management.DOI:http://dx.doi.org/10.7554/eLife.15175.003. Diagnostic potential of tumor DNA from ovarian cyst fluid. Wang Y, Sundfeldt K, Mateoiu C, Shih IeM, Kurman RJ, Schaefer J, Silliman N, Kinde I, Springer S, Foote M, Kristjansdottir B, James N, Kinzler KW, Papadopoulos N, Diaz LA, Vogelstein B - eLife (2016). Not Altered. CC.